feat(chat-room): 대화 설정 다이얼로그 구현 및 채팅방 초기화 API 연동

- MoreDialog UI 구성 및 동작(배경 스위치/변경, 대화 초기화, 신고하기)
- 방별 배경 표시 SharedPreferences 저장 및 화면 반영
- TalkApi에 resetChatRoom 엔드포인트 추가, Repository 메서드 추가
- ChatRoomActivity와 다이얼로그 연동, 초기화 플로우 구현

app/src/main/java/kr/co/vividnext/sodalive/chat/talk/TalkApi.kt

@@ -28,6 +28,13 @@ interface TalkApi {
         @Body request: CreateChatRoomRequest
     ): Single<ApiResponse<CreateChatRoomResponse>>
 
+    // 채팅방 초기화 API (채팅방 생성 응답과 동일 구조 반환)
+    @POST("/api/chat/room/{roomId}/reset")
+    fun resetChatRoom(
+        @Header("Authorization") authHeader: String,
+        @Path("roomId") roomId: Long
+    ): Single<ApiResponse<CreateChatRoomResponse>>
+
     // 통합 채팅방 입장 API
     @GET("/api/chat/room/{roomId}/enter")
     fun enterChatRoom(

app/src/main/java/kr/co/vividnext/sodalive/chat/talk/room/ChatRepository.kt

@@ -184,4 +184,13 @@ class ChatRepository(
                 insert.andThen(Single.just(serverMsg)).subscribeOn(Schedulers.io())
             }
     }
+
+    /**
+     * 대화 초기화: 서버에 리셋 요청 → 새 채팅방 ID 반환
+     */
+    fun resetChatRoom(token: String, roomId: Long): Single<CreateChatRoomResponse> {
+        return talkApi.resetChatRoom(authHeader = token, roomId = roomId)
+            .subscribeOn(Schedulers.io())
+            .map { ensureSuccess(it) }
+    }
 }

app/src/main/java/kr/co/vividnext/sodalive/chat/talk/room/ChatRoomActivity.kt

@@ -67,6 +67,8 @@ class ChatRoomActivity : BaseActivity<ActivityChatRoomBinding>(
         setupRecyclerView()
         setupInputArea()
         loadInitialMessages()
+        // 배경 표시 설정 적용
+        applyBackgroundVisibility()
     }
 
     @SuppressLint("SetTextI18n")
@@ -78,7 +80,7 @@ class ChatRoomActivity : BaseActivity<ActivityChatRoomBinding>(
 
         // 더보기 클릭 시 전체화면 다이얼로그 표시
         binding.ivMore.setOnClickListener {
-            ChatRoomMoreDialogFragment().show(supportFragmentManager, "ChatRoomMoreDialog")
+            ChatRoomMoreDialogFragment.newInstance(roomId).show(supportFragmentManager, "ChatRoomMoreDialog")
         }
 
         // 5.3: characterInfo가 있으면 헤더 바인딩, 없으면 기본 플레이스홀더 유지
@@ -685,6 +687,39 @@ class ChatRoomActivity : BaseActivity<ActivityChatRoomBinding>(
         dialog.show(supportFragmentManager, "ChatImageCarousel")
     }
 
+    fun applyBackgroundVisibility() {
+        val visible = prefs.getBoolean("chat_bg_visible_room_$roomId", true)
+        binding.ivBackgroundProfile.isVisible = visible
+        binding.viewCharacterDim.isVisible = visible
+    }
+
+    fun onResetChatRequested() {
+        val title = "대화 초기화"
+        val desc = "지금까지의 대화가 모두 초기화 되고 새롭게 대화를 시작합니다."
+        SodaDialog(
+            activity = this,
+            layoutInflater = this.layoutInflater,
+            title = title,
+            desc = desc,
+            confirmButtonTitle = "초기화",
+            confirmButtonClick = {
+                val token = "Bearer ${SharedPreferenceManager.token}"
+                val disposable = chatRepository.resetChatRoom(token = token, roomId = roomId)
+                    .observeOn(AndroidSchedulers.mainThread())
+                    .subscribe({ response ->
+                        val intent = newIntent(this, response.chatRoomId)
+                        startActivity(intent)
+                        finish()
+                    }, { error ->
+                        showToast(error.message ?: "대화 초기화에 실패했어요.")
+                    })
+                compositeDisposable.add(disposable)
+            },
+            cancelButtonTitle = "취소",
+            cancelButtonClick = { /* no-op */ }
+        ).show(resources.displayMetrics.widthPixels)
+    }
+
     companion object {
         const val EXTRA_ROOM_ID: String = "extra_room_id"
 

app/src/main/java/kr/co/vividnext/sodalive/chat/talk/room/ChatRoomMoreDialogFragment.kt

@@ -1,15 +1,23 @@
 package kr.co.vividnext.sodalive.chat.talk.room
 
+import android.content.Context
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import android.widget.ImageView
+import android.widget.LinearLayout
 import androidx.fragment.app.DialogFragment
+import com.google.android.material.switchmaterial.SwitchMaterial
 import kr.co.vividnext.sodalive.R
+import kr.co.vividnext.sodalive.base.SodaDialog
 
 /**
  * 채팅방 우측 상단 더보기 버튼 클릭 시 표시되는 전체화면 다이얼로그.
- * 내용은 추후 구성 예정이며 현재는 플레이스홀더 UI만 표시합니다.
+ * - 배경 사진 표시 스위치
+ * - 배경 사진 변경(추후 상세 다이얼로그 예정)
+ * - 대화 초기화(확인 후 API 호출은 Activity에서 처리)
+ * - 신고하기(임시 안내)
  */
 class ChatRoomMoreDialogFragment : DialogFragment() {
 
@@ -26,4 +34,73 @@ class ChatRoomMoreDialogFragment : DialogFragment() {
     ): View? {
         return inflater.inflate(R.layout.fragment_chat_room_more_dialog, container, false)
     }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        val roomId = arguments?.getLong(ARG_ROOM_ID) ?: 0L
+
+        // 닫기 버튼
+        view.findViewById<ImageView>(R.id.iv_close)?.setOnClickListener { dismiss() }
+
+        val prefs = requireActivity().getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE)
+        val bgKey = bgPrefKey(roomId)
+
+        val switch = view.findViewById<SwitchMaterial>(R.id.sw_background)
+        switch?.isChecked = prefs.getBoolean(bgKey, true)
+        switch?.setOnCheckedChangeListener { _, isChecked ->
+            prefs.edit().putBoolean(bgKey, isChecked).apply()
+            (activity as? ChatRoomActivity)?.applyBackgroundVisibility()
+        }
+
+        // 행 클릭 시 스위치 토글
+        view.findViewById<LinearLayout>(R.id.row_bg_switch)?.setOnClickListener {
+            switch?.toggle()
+        }
+
+        // 배경 사진 변경 (임시 안내)
+        view.findViewById<LinearLayout>(R.id.row_bg_change)?.setOnClickListener {
+            // TODO: 배경 선택 다이얼로그 연결 (기본 프로필 + 구매한 캐릭터 이미지)
+            SodaDialog(
+                requireActivity(),
+                layoutInflater,
+                title = getString(R.string.app_name),
+                desc = "배경 사진 변경은 곧 제공됩니다.",
+                confirmButtonTitle = "확인",
+                confirmButtonClick = {},
+                cancelButtonTitle = ""
+            ).show(resources.displayMetrics.widthPixels)
+        }
+
+        // 대화 초기화: Activity에 위임
+        view.findViewById<LinearLayout>(R.id.row_reset)?.setOnClickListener {
+            (activity as? ChatRoomActivity)?.onResetChatRequested()
+        }
+
+        // 신고하기 (임시 안내)
+        view.findViewById<LinearLayout>(R.id.row_report)?.setOnClickListener {
+            SodaDialog(
+                requireActivity(),
+                layoutInflater,
+                title = "신고하기",
+                desc = "신고하기 기능은 준비 중입니다.",
+                confirmButtonTitle = "확인",
+                confirmButtonClick = {},
+                cancelButtonTitle = ""
+            ).show(resources.displayMetrics.widthPixels)
+        }
+    }
+
+    companion object {
+        private const val ARG_ROOM_ID = "arg_room_id"
+        private const val PREFS_NAME = "chat_room_prefs"
+        private fun bgPrefKey(roomId: Long) = "chat_bg_visible_room_$roomId"
+
+        fun newInstance(roomId: Long): ChatRoomMoreDialogFragment {
+            val f = ChatRoomMoreDialogFragment()
+            val args = Bundle()
+            args.putLong(ARG_ROOM_ID, roomId)
+            f.arguments = args
+            return f
+        }
+    }
 }

app/src/main/res/layout/fragment_chat_room_more_dialog.xml

@@ -1,20 +1,165 @@
 <?xml version="1.0" encoding="utf-8"?>
 <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:background="#CC000000">
+    android:background="@color/color_131313">
 
-    <TextView
-        android:id="@+id/tv_placeholder"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="준비중"
-        android:textColor="@android:color/white"
-        android:textSize="18sp"
-        app:layout_constraintBottom_toBottomOf="parent"
+    <!-- DetailToolbar -->
+    <LinearLayout
+        android:id="@+id/toolbar"
+        android:layout_width="0dp"
+        android:layout_height="56dp"
+        android:background="@android:color/transparent"
+        android:gravity="center_vertical"
+        android:orientation="horizontal"
+        android:paddingStart="16dp"
+        android:paddingEnd="16dp"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+        app:layout_constraintTop_toTopOf="parent">
+
+        <ImageView
+            android:id="@+id/iv_close"
+            android:layout_width="24dp"
+            android:layout_height="24dp"
+            android:contentDescription="@string/a11y_back"
+            android:src="@drawable/ic_back"/>
+
+        <TextView
+            android:id="@+id/tv_title"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="12dp"
+            android:ellipsize="end"
+            android:fontFamily="@font/pretendard_bold"
+            android:maxLines="1"
+            android:text="대화 설정"
+            android:textColor="#FFFFFFFF"
+            android:textSize="18sp"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toEndOf="@id/iv_close"
+            tools:text="대화 설정" />
+    </LinearLayout>
+
+    <androidx.core.widget.NestedScrollView
+        android:id="@+id/scroll"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
+        app:layout_constraintTop_toBottomOf="@id/toolbar"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical">
+
+            <!-- 배경 사진 스위치 -->
+            <LinearLayout
+                android:id="@+id/row_bg_switch"
+                android:layout_width="match_parent"
+                android:layout_height="56dp"
+                android:gravity="center_vertical"
+                android:orientation="horizontal"
+                android:paddingStart="20dp"
+                android:paddingEnd="20dp">
+
+                <TextView
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:text="배경 사진"
+                    android:textColor="#FFFFFFFF"
+                    android:textSize="16sp" />
+
+                <com.google.android.material.switchmaterial.SwitchMaterial
+                    android:id="@+id/sw_background"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content" />
+            </LinearLayout>
+
+            <View
+                android:layout_width="match_parent"
+                android:layout_height="1dp"
+                android:background="#26FFFFFF" />
+
+            <!-- 배경 사진 변경 -->
+            <LinearLayout
+                android:id="@+id/row_bg_change"
+                android:layout_width="match_parent"
+                android:layout_height="56dp"
+                android:gravity="center_vertical"
+                android:orientation="horizontal"
+                android:paddingStart="20dp"
+                android:paddingEnd="20dp">
+
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="배경 사진 변경"
+                    android:textColor="#FFFFFFFF"
+                    android:textSize="16sp" />
+            </LinearLayout>
+
+            <View
+                android:layout_width="match_parent"
+                android:layout_height="1dp"
+                android:background="#26FFFFFF" />
+
+            <!-- 대화 초기화 -->
+            <LinearLayout
+                android:id="@+id/row_reset"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="vertical"
+                android:paddingStart="20dp"
+                android:paddingEnd="20dp"
+                android:paddingTop="12dp"
+                android:paddingBottom="12dp">
+
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="대화 초기화"
+                    android:textColor="#FFFFFFFF"
+                    android:textSize="16sp" />
+
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_marginTop="6dp"
+                    android:text="지금까지의 대화가 모두 초기화 되고 새롭게 대화를 시작합니다."
+                    android:textColor="#B3FFFFFF"
+                    android:textSize="13sp" />
+            </LinearLayout>
+
+            <View
+                android:layout_width="match_parent"
+                android:layout_height="1dp"
+                android:background="#26FFFFFF" />
+
+            <!-- 신고하기 -->
+            <LinearLayout
+                android:id="@+id/row_report"
+                android:layout_width="match_parent"
+                android:layout_height="56dp"
+                android:gravity="center_vertical"
+                android:orientation="horizontal"
+                android:paddingStart="20dp"
+                android:paddingEnd="20dp">
+
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="신고하기"
+                    android:textColor="#FFFFFFFF"
+                    android:textSize="16sp" />
+            </LinearLayout>
+
+        </LinearLayout>
+    </androidx.core.widget.NestedScrollView>
 
 </androidx.constraintlayout.widget.ConstraintLayout>