feat(quota)!: AI 채팅 쿼터(무료/유료) 도입 및 입장/전송 응답에 상태 포함

- ChatQuota 엔티티/레포/서비스/컨트롤러 추가
- 입장 시 Lazy refill 적용, 전송 시 무료 우선 차감 및 잔여/리필 시간 응답 포함
- ChatRoomEnterResponse에 totalRemaining/nextRechargeAtEpoch 추가
- SendChatMessageResponse 신설 및 send API 응답 스키마 변경
- CanUsage에 CHAT_QUOTA_PURCHASE 추가, CanPaymentService/CanService에 결제 흐름 반영

src/main/kotlin/kr/co/vividnext/sodalive/chat/room/dto/ChatRoomDto.kt

@@ -180,5 +180,16 @@ data class ChatRoomEnterResponse(
     val roomId: Long,
     val character: ChatRoomEnterCharacterDto,
     val messages: List<ChatMessageItemDto>,
-    val hasMoreMessages: Boolean
+    val hasMoreMessages: Boolean,
+    val totalRemaining: Int,
+    val nextRechargeAtEpoch: Long?
+)
+
+/**
+ * 채팅 메시지 전송 응답 DTO (메시지 + 쿼터 상태)
+ */
+data class SendChatMessageResponse(
+    val messages: List<ChatMessageItemDto>,
+    val totalRemaining: Int,
+    val nextRechargeAtEpoch: Long?
 )

src/main/kotlin/kr/co/vividnext/sodalive/chat/room/service/ChatRoomService.kt

@@ -19,6 +19,7 @@ import kr.co.vividnext.sodalive.chat.room.dto.CreateChatRoomResponse
 import kr.co.vividnext.sodalive.chat.room.dto.ExternalChatSendResponse
 import kr.co.vividnext.sodalive.chat.room.dto.ExternalChatSessionCreateResponse
 import kr.co.vividnext.sodalive.chat.room.dto.ExternalChatSessionGetResponse
+import kr.co.vividnext.sodalive.chat.room.dto.SendChatMessageResponse
 import kr.co.vividnext.sodalive.chat.room.repository.ChatMessageRepository
 import kr.co.vividnext.sodalive.chat.room.repository.ChatParticipantRepository
 import kr.co.vividnext.sodalive.chat.room.repository.ChatRoomRepository
@@ -49,6 +50,7 @@ class ChatRoomService(
     private val characterImageService: CharacterImageService,
     private val canPaymentService: kr.co.vividnext.sodalive.can.payment.CanPaymentService,
     private val imageCloudFront: kr.co.vividnext.sodalive.aws.cloudfront.ImageContentCloudFront,
+    private val chatQuotaService: kr.co.vividnext.sodalive.chat.quota.ChatQuotaService,
 
     @Value("\${weraser.api-key}")
     private val apiKey: String,
@@ -335,11 +337,16 @@ class ChatRoomService(
         val messagesAsc = fetched.sortedBy { it.createdAt }
         val items = messagesAsc.map { toChatMessageItemDto(it, member) }
 
+        // 입장 시 Lazy refill 적용 후 상태 반환
+        val quotaStatus = chatQuotaService.applyRefillOnEnterAndGetStatus(member.id!!)
+
         return ChatRoomEnterResponse(
             roomId = room.id!!,
             character = characterDto,
             messages = items,
-            hasMoreMessages = hasMore
+            hasMoreMessages = hasMore,
+            totalRemaining = quotaStatus.totalRemaining,
+            nextRechargeAtEpoch = quotaStatus.nextRechargeAtEpochMillis
         )
     }
 
@@ -490,7 +497,7 @@ class ChatRoomService(
     }
 
     @Transactional
-    fun sendMessage(member: Member, chatRoomId: Long, message: String): List<ChatMessageItemDto> {
+    fun sendMessage(member: Member, chatRoomId: Long, message: String): SendChatMessageResponse {
         // 1) 방 존재 확인
         val room = chatRoomRepository.findById(chatRoomId).orElseThrow {
             SodaException("채팅방을 찾을 수 없습니다.")
@@ -512,7 +519,10 @@ class ChatRoomService(
         val sessionId = room.sessionId
         val characterUUID = character.characterUUID
 
-        // 5) 외부 API 호출 (최대 3회 재시도)
+        // 5) 쿼터 확인 및 차감
+        chatQuotaService.consumeOne(member.id!!)
+
+        // 6) 외부 API 호출 (최대 3회 재시도)
         val characterReply = callExternalApiForChatSendWithRetry(userId, characterUUID, message, sessionId)
 
         // 6) 내 메시지 저장
@@ -553,6 +563,8 @@ class ChatRoomService(
             hasAccess = true
         )
 
+        val status = chatQuotaService.getStatus(member.id!!)
+
         // 8) 트리거 매칭 → 이미지 메시지 추가 저장(있을 경우)
         val matchedImage = findTriggeredCharacterImage(character.id!!, characterReply)
         if (matchedImage != null) {
@@ -579,10 +591,18 @@ class ChatRoomService(
             )
 
             val imageDto = toChatMessageItemDto(imageMsg, member)
-            return listOf(textDto, imageDto)
+            return SendChatMessageResponse(
+                messages = listOf(textDto, imageDto),
+                totalRemaining = status.totalRemaining,
+                nextRechargeAtEpoch = status.nextRechargeAtEpochMillis
+            )
         }
 
-        return listOf(textDto)
+        return SendChatMessageResponse(
+            messages = listOf(textDto),
+            totalRemaining = status.totalRemaining,
+            nextRechargeAtEpoch = status.nextRechargeAtEpochMillis
+        )
     }
 
     private fun toChatMessageItemDto(