feat(settings): add app visibility settings

Allow users to choose which apps (Claude, Codex, Gemini, OpenCode) to display on the homepage.

- Add VisibleApps type and settings field in both frontend and backend
- Refactor AppSwitcher to render apps dynamically based on visibility
- Extract ToggleRow component for reuse
- Add i18n support for app visibility settings

src/types.ts

@@ -137,6 +137,14 @@ export interface ProviderMeta {
   proxyConfig?: ProviderProxyConfig;
 }
 
+// 主页面显示的应用配置
+export interface VisibleApps {
+  claude: boolean;
+  codex: boolean;
+  gemini: boolean;
+  opencode: boolean;
+}
+
 // 应用设置类型（用于设置对话框与 Tauri API）
 // 存储在本地 ~/.cc-switch/settings.json，不随数据库同步
 export interface Settings {
@@ -154,6 +162,9 @@ export interface Settings {
   // 首选语言（可选，默认中文）
   language?: "en" | "zh" | "ja";
 
+  // 主页面显示的应用（默认全部显示）
+  visibleApps?: VisibleApps;
+
   // ===== 设备级目录覆盖 =====
   // 覆盖 Claude Code 配置目录（可选）
   claudeConfigDir?: string;