feat(chat): 채팅 탭 추가 및 캐릭터/톡 내부 탭 구현

- ChatTabView 신설: 앱 바 + 내부 탭(캐릭터/톡) 전환 구성
- 커스텀 탭 적용
  - indicatorHeight: 4, indicatorColor: #3bb9f1
  - tabText color: #b0bec5
  - 폰트: 선택 전 Pretendard-Regular, 선택 후 Pretendard-Bold
- HomeView/BottomTabView에 ChatTabView 연동
- CharacterView/TalkView 플레이스홀더 추가

.gitignore

@@ -7,6 +7,7 @@
 # Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
 
 # User-specific stuff
+.idea/
 .idea/**/workspace.xml
 .idea/**/tasks.xml
 .idea/**/usage.statistics.xml
@@ -276,4 +277,7 @@ xcuserdata
 /*.gcno
 **/xcshareddata/WorkspaceSettings.xcsettings
 
+.kiro/
+.junie/
+
 # End of https://www.toptal.com/developers/gitignore/api/macos,xcode,appcode,swift,swiftpackagemanager,swiftpm,fastlane,cocoapods