feat(character): 캐릭터 메인 화면 구현 및 Combine 기반 리팩터링

- 배너/최근/신규/큐레이션 섹션 UI 구성 및 데이터 바인딩
- 네트워크 이미지 로더를 Kingfisher(KFImage)로 교체하여 캐싱/재시도 지원
- CharacterApi에 토큰 헤더 포함, GET /api/chat/character/main 연동

SodaLive/Sources/Chat/Character/Banner/AutoSlideCharacterBannerView.swift

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+//
+//  AutoSlideCharacterBannerView.swift
+//  SodaLive
+//
+//  Created by klaus on 8/29/25.
+//
+
+import SwiftUI
+import Kingfisher
+
+struct AutoSlideCharacterBannerView: View {
+    var items: [CharacterBannerResponse] = []
+    var onTap: (CharacterBannerResponse) -> Void = { _ in }
+    
+    @State private var index: Int = 0
+    @State private var height: CGFloat = 0
+    private let timer = Timer.publish(every: 4, on: .main, in: .common).autoconnect()
+    
+    var body: some View {
+        TabView(selection: $index) {
+            ForEach(0..<items.count, id: \.self) { index in
+                let item = items[index]
+                KFImage(URL(string: item.imageUrl))
+                    .placeholder { Color.gray.opacity(0.2) }
+                    .retry(maxCount: 2, interval: .seconds(1))
+                    .cancelOnDisappear(true)
+                    .resizable()
+                    .scaledToFill()
+                    .frame(height: height)
+                    .clipped()
+                    .cornerRadius(12)
+                    .contentShape(Rectangle())
+                    .tag(index)
+                    .onTapGesture { onTap(item) }
+            }
+        }
+        .tabViewStyle(.page(indexDisplayMode: .automatic))
+        .frame(maxWidth: .infinity)
+        .frame(height: height)
+        .onAppear {
+            self.height = screenSize().width * 0.53
+        }
+        .onDisappear {
+            timer.upstream.connect().cancel()
+        }
+        .onReceive(timer) { _ in
+            guard !items.isEmpty else { return }
+            withAnimation { index = (index + 1) % items.count }
+        }
+    }
+}
+
+#Preview {
+    AutoSlideCharacterBannerView(
+        items: [
+            CharacterBannerResponse(characterId: 1, imageUrl: "https://picsum.photos/1000/300")
+        ]
+    )
+    .padding()
+    .background(Color.black)
+}

SodaLive/Sources/Chat/Character/Banner/CharacterBannerResponse.swift

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+//
+//  CharacterBannerResponse.swift
+//  SodaLive
+//
+//  Created by klaus on 8/29/25.
+//
+
+struct CharacterBannerResponse: Decodable {
+    let characterId: Int
+    let imageUrl: String
+}