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

SodaLive/Sources/Main/Home/BottomTabView.swift

@@ -13,7 +13,7 @@ struct BottomTabView: View {
     
     var body: some View {
         HStack(spacing: 0) {
-            let tabWidth = width / 3
+            let tabWidth = width / 4
             
             TabButton(
                 title: "홈",
@@ -40,6 +40,31 @@ struct BottomTabView: View {
                 width: tabWidth
             )
             
+            TabButton(
+                title: "채팅",
+                action: {
+                    if currentTab != .chat {
+                        currentTab = .chat
+                    }
+                },
+                image: {
+                    currentTab == .chat ?
+                    "ic_chat_selected" :
+                    "ic_chat"
+                },
+                fontName: {
+                    currentTab == .chat ?
+                    Font.bold.rawValue :
+                    Font.medium.rawValue
+                },
+                color: {
+                    currentTab == .chat ?
+                    Color.button :
+                    Color.graybb
+                },
+                width: tabWidth
+            )
+            
             TabButton(
                 title: "라이브",
                 action: {

SodaLive/Sources/Main/Home/HomeView.swift

@@ -19,6 +19,7 @@ struct HomeView: View {
     
     private let liveView = LiveView()
     private let homeTabView = HomeTabView()
+    private let chatTabView = ChatTabView()
     
     @State private var isShowPlayer = false
     @AppStorage("token") private var token: String = UserDefaults.string(forKey: UserDefaultsKey.token)
@@ -32,6 +33,10 @@ struct HomeView: View {
                             .frame(width: viewModel.currentTab == .home ? proxy.size.width : 0)
                             .opacity(viewModel.currentTab == .home ? 1.0 : 0.01)
                         
+                        chatTabView
+                            .frame(width: viewModel.currentTab == .chat ? proxy.size.width : 0)
+                            .opacity(viewModel.currentTab == .chat ? 1.0 : 0.01)
+                        
                         liveView
                             .frame(width: viewModel.currentTab == .live ? proxy.size.width : 0)
                             .opacity(viewModel.currentTab == .live ? 1.0 : 0.01)

SodaLive/Sources/Main/Home/HomeViewModel.swift

@@ -18,7 +18,7 @@ final class HomeViewModel: ObservableObject {
     private let playbackTrackingRepository = PlaybackTrackingRepository()
     
     enum CurrentTab: String {
-        case home, live, mypage
+        case home, chat, live, mypage
     }
     
     @Published var currentTab: CurrentTab = AppState.shared.startTab