fix(character): 인기 캐릭터 응답을 DTO로 변경하여 jackson 직렬화 오류 해결

- ChatCharacterService.getPopularCharacters 반환을 List<ChatCharacter> → List<Character> DTO로 변경
- 캐시 대상도 DTO로 전환(@Cacheable 유지, 동적 키/고정 TTL 그대로 사용)
- 컨트롤러에서 불필요한 매핑 제거(서비스가 DTO로 반환)
- Character DTO 직렬화 안정성 확보(@JsonProperty 추가)
- 이미지 URL 생성 로직을 서비스로 이동하고 imageHost(@Value) 주입해 구성

src/main/kotlin/kr/co/vividnext/sodalive/chat/character/controller/ChatCharacterController.kt

@@ -66,14 +66,6 @@ class ChatCharacterController(
 
         // 인기 캐릭터 조회
         val popularCharacters = service.getPopularCharacters()
-            .map {
-                Character(
-                    characterId = it.id!!,
-                    name = it.name,
-                    description = it.description,
-                    imageUrl = "$imageHost/${it.imagePath ?: "profile/default-profile.png"}"
-                )
-            }
 
         // 최신 캐릭터 조회 (최대 10개)
         val newCharacters = service.getNewCharacters(50)

src/main/kotlin/kr/co/vividnext/sodalive/chat/character/dto/CharacterHomeResponse.kt

@@ -1,5 +1,7 @@
 package kr.co.vividnext.sodalive.chat.character.dto
 
+import com.fasterxml.jackson.annotation.JsonProperty
+
 data class CharacterMainResponse(
     val banners: List<CharacterBannerResponse>,
     val recentCharacters: List<RecentCharacter>,
@@ -15,10 +17,10 @@ data class CurationSection(
 )
 
 data class Character(
-    val characterId: Long,
+    @JsonProperty("characterId") val characterId: Long,
-    val name: String,
+    @JsonProperty("name") val name: String,
-    val description: String,
+    @JsonProperty("description") val description: String,
-    val imageUrl: String
+    @JsonProperty("imageUrl") val imageUrl: String
 )
 
 data class RecentCharacter(

src/main/kotlin/kr/co/vividnext/sodalive/chat/character/service/ChatCharacterService.kt

@@ -11,11 +11,13 @@ import kr.co.vividnext.sodalive.chat.character.ChatCharacterGoal
 import kr.co.vividnext.sodalive.chat.character.ChatCharacterHobby
 import kr.co.vividnext.sodalive.chat.character.ChatCharacterTag
 import kr.co.vividnext.sodalive.chat.character.ChatCharacterValue
+import kr.co.vividnext.sodalive.chat.character.dto.Character
 import kr.co.vividnext.sodalive.chat.character.repository.ChatCharacterGoalRepository
 import kr.co.vividnext.sodalive.chat.character.repository.ChatCharacterHobbyRepository
 import kr.co.vividnext.sodalive.chat.character.repository.ChatCharacterRepository
 import kr.co.vividnext.sodalive.chat.character.repository.ChatCharacterTagRepository
 import kr.co.vividnext.sodalive.chat.character.repository.ChatCharacterValueRepository
+import org.springframework.beans.factory.annotation.Value
 import org.springframework.cache.annotation.Cacheable
 import org.springframework.data.domain.PageRequest
 import org.springframework.stereotype.Service
@@ -28,7 +30,10 @@ class ChatCharacterService(
     private val valueRepository: ChatCharacterValueRepository,
     private val hobbyRepository: ChatCharacterHobbyRepository,
     private val goalRepository: ChatCharacterGoalRepository,
-    private val popularCharacterQuery: PopularCharacterQuery
+    private val popularCharacterQuery: PopularCharacterQuery,
+
+    @Value("\${cloud.aws.cloud-front.host}")
+    private val imageHost: String
 ) {
     /**
      * UTC 20:00 경계 기준 지난 윈도우의 메시지 수 상위 캐릭터 조회
@@ -39,10 +44,18 @@ class ChatCharacterService(
         cacheNames = ["popularCharacters_24h"],
         key = "T(kr.co.vividnext.sodalive.chat.character.service.RankingWindowCalculator).now('popular-chat-character').cacheKey"
     )
-    fun getPopularCharacters(limit: Long = 20): List<ChatCharacter> {
+    fun getPopularCharacters(limit: Long = 20): List<Character> {
         val window = RankingWindowCalculator.now("popular-chat-character")
         val topIds = popularCharacterQuery.findPopularCharacterIds(window.windowStart, window.nextBoundary, limit)
-        return loadCharactersInOrder(topIds)
+        val list = loadCharactersInOrder(topIds)
+        return list.map {
+            Character(
+                characterId = it.id!!,
+                name = it.name,
+                description = it.description,
+                imageUrl = "$imageHost/${it.imagePath ?: "profile/default-profile.png"}"
+            )
+        }
     }
 
     private fun loadCharactersInOrder(ids: List<Long>): List<ChatCharacter> {