feat(character-comment): 답글 리스트 API 연동 및 커서 기반 무한 스크롤 적용

feat(character-comment): 답글 작성 API 연동 및 성공 시 낙관적 UI 반영

- CharacterCommentReplyFragment에 listReplies API 연동
- 초기 1회 로드 허용, 이후 cursor != null일 때만 추가 로드
- isLoading 플래그로 중복 요청 방지
- 어댑터 헤더(원본 댓글) 유지, replies만 순차 추가

- CharacterCommentReplyFragment에서 createReply API 호출로 스텁 제거
- 요청 중 로딩 다이얼로그 표시, 성공 시 입력 초기화 및 리스트에 즉시 추가
- 에러 처리(토스트) 적용

app/src/main/java/kr/co/vividnext/sodalive/chat/character/comment/CharacterCommentReplyFragment.kt

@@ -12,14 +12,14 @@ import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import coil.load
 import coil.transform.CircleCropTransformation
+import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers
+import io.reactivex.rxjava3.schedulers.Schedulers
 import kr.co.vividnext.sodalive.R
 import kr.co.vividnext.sodalive.base.BaseFragment
 import kr.co.vividnext.sodalive.common.LoadingDialog
 import kr.co.vividnext.sodalive.common.SharedPreferenceManager
 import kr.co.vividnext.sodalive.databinding.FragmentCharacterCommentReplyBinding
 import kr.co.vividnext.sodalive.extensions.dpToPx
-import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers
-import io.reactivex.rxjava3.schedulers.Schedulers
 import org.koin.android.ext.android.inject
 
 /**
@@ -93,7 +93,21 @@ class CharacterCommentReplyFragment : BaseFragment<FragmentCharacterCommentReply
             hideKeyboard()
             val text = binding.etComment.text.toString()
             if (text.isBlank()) return@setOnClickListener
-            // 스텁: 로컬에 즉시 추가
+            val originalId = original?.commentId ?: return@setOnClickListener
+            val token = "Bearer ${SharedPreferenceManager.token}"
+            loadingDialog.show(screenWidth)
+            val d = repository.createReply(
+                characterId = characterId,
+                commentId = originalId,
+                comment = text,
+                token = token
+            )
+                .subscribeOn(Schedulers.io())
+                .observeOn(AndroidSchedulers.mainThread())
+                .doFinally { loadingDialog.dismiss() }
+                .subscribe({ resp ->
+                    if (resp.success) {
+                        // 성공 시 낙관적 UI 반영: 기존 스텁과 동일하게 즉시 목록에 추가
                         val me = CharacterReplyResponse(
                             replyId = System.currentTimeMillis(),
                             memberId = SharedPreferenceManager.userId,
@@ -107,7 +121,21 @@ class CharacterCommentReplyFragment : BaseFragment<FragmentCharacterCommentReply
                         adapter.notifyItemInserted(insertAt)
                         binding.rvCommentReply.scrollToPosition(adapter.items.size - 1)
                         binding.etComment.setText("")
-            Toast.makeText(requireContext(), "등록되었습니다 (stub)", Toast.LENGTH_SHORT).show()
+                    } else {
+                        Toast.makeText(
+                            requireContext(),
+                            resp.message ?: "요청 중 오류가 발생했습니다",
+                            Toast.LENGTH_SHORT
+                        ).show()
+                    }
+                }, { e ->
+                    Toast.makeText(
+                        requireContext(),
+                        e.message ?: "요청 중 오류가 발생했습니다",
+                        Toast.LENGTH_SHORT
+                    ).show()
+                })
+            compositeDisposable.add(d)
         }
 
         adapter = CharacterCommentReplyAdapter(
@@ -134,16 +162,30 @@ class CharacterCommentReplyFragment : BaseFragment<FragmentCharacterCommentReply
 
         val recyclerView = binding.rvCommentReply
         recyclerView.setHasFixedSize(true)
-        recyclerView.layoutManager = LinearLayoutManager(activity, LinearLayoutManager.VERTICAL, false)
+        recyclerView.layoutManager =
+            LinearLayoutManager(activity, LinearLayoutManager.VERTICAL, false)
         recyclerView.addItemDecoration(object : RecyclerView.ItemDecoration() {
-            override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
+            override fun getItemOffsets(
+                outRect: Rect,
+                view: View,
+                parent: RecyclerView,
+                state: RecyclerView.State
+            ) {
                 super.getItemOffsets(outRect, view, parent, state)
                 outRect.left = 13.3f.dpToPx().toInt()
                 outRect.right = 13.3f.dpToPx().toInt()
                 when (parent.getChildAdapterPosition(view)) {
-                    0 -> { outRect.top = 13.3f.dpToPx().toInt(); outRect.bottom = 12f.dpToPx().toInt() }
-                    adapter.itemCount - 1 -> { outRect.top = 12f.dpToPx().toInt(); outRect.bottom = 13.3f.dpToPx().toInt() }
-                    else -> { outRect.top = 12f.dpToPx().toInt(); outRect.bottom = 12f.dpToPx().toInt() }
+                    0 -> {
+                        outRect.top = 13.3f.dpToPx().toInt(); outRect.bottom = 12f.dpToPx().toInt()
+                    }
+
+                    adapter.itemCount - 1 -> {
+                        outRect.top = 12f.dpToPx().toInt(); outRect.bottom = 13.3f.dpToPx().toInt()
+                    }
+
+                    else -> {
+                        outRect.top = 12f.dpToPx().toInt(); outRect.bottom = 12f.dpToPx().toInt()
+                    }
                 }
             }
         })
@@ -218,12 +260,16 @@ class CharacterCommentReplyFragment : BaseFragment<FragmentCharacterCommentReply
         private const val EXTRA_CHARACTER_ID = "extra_character_id"
         private const val EXTRA_ORIGINAL_COMMENT_ID = "extra_original_comment_id"
         private const val EXTRA_ORIGINAL_MEMBER_ID = "extra_original_member_id"
-        private const val EXTRA_ORIGINAL_MEMBER_PROFILE_IMAGE = "extra_original_member_profile_image"
+        private const val EXTRA_ORIGINAL_MEMBER_PROFILE_IMAGE =
+            "extra_original_member_profile_image"
         private const val EXTRA_ORIGINAL_MEMBER_NICKNAME = "extra_original_member_nickname"
         private const val EXTRA_ORIGINAL_CREATED_AT = "extra_original_created_at"
         private const val EXTRA_ORIGINAL_REPLY_COUNT = "extra_original_reply_count"
         private const val EXTRA_ORIGINAL_COMMENT_TEXT = "extra_original_comment_text"
-        fun newInstance(characterId: Long, original: CharacterCommentResponse): CharacterCommentReplyFragment {
+        fun newInstance(
+            characterId: Long,
+            original: CharacterCommentResponse
+        ): CharacterCommentReplyFragment {
             val args = Bundle().apply {
                 putLong(EXTRA_CHARACTER_ID, characterId)
                 putLong(EXTRA_ORIGINAL_COMMENT_ID, original.commentId)