feat: add Universal Provider feature (#348)

* feat: add Universal Provider feature

- Add Universal Provider data structures and type definitions
- Implement backend CRUD operations and sync functionality
- Add frontend UI components (UniversalProviderPanel, Card, FormModal)
- Add NewAPI icon and preset configuration
- Support cross-app (Claude/Codex/Gemini) configuration sync
- Add website URL field for providers
- Implement real-time refresh via event notifications
- Add i18n support (Chinese/English/Japanese)

* feat: integrate universal provider presets into add provider dialog

- Add universal provider presets (NewAPI, Custom Gateway) to preset selector
- Show universal presets with Layers icon badge in preset selector
- Open UniversalProviderFormModal when universal preset is clicked
- Pass initialPreset to auto-fill form when opened from add dialog
- Add i18n keys for addSuccess/addFailed messages
- Keep separate universal provider panel for management

* refactor: move universal provider management to add dialog

- Remove Layers button from main navigation header
- Add 'Manage' button next to universal provider presets
- Open UniversalProviderPanel from within add provider dialog
- Add i18n keys for 'manage' in all locales

* style: display universal provider presets on separate line

- Move universal provider section to a new row with border separator
- Add label '统一供应商:' to clarify the section

* style: unify universal provider label style with preset label

- Use FormLabel component for consistent styling
- Add background to 'Manage' button matching preset buttons
- Update icon size and button padding for consistency

* feat: add sync functionality and JSON preview for Universal Provider

* fix: add missing in_failover_queue field to Provider structs

After rebasing to main, the Provider struct gained a new
`in_failover_queue` field. This fix adds the missing field
to the three to_*_provider() methods in UniversalProvider.

* refactor: redesign AddProviderDialog with tab-based layout

- Add tabs to separate app-specific providers and universal providers
- Move "Add Universal Provider" button from panel header to footer
- Remove unused handleAdd callback and clean up imports
- Update emptyHint i18n text to reference the footer button

* fix: append /v1 suffix to Codex base_url in Universal Provider

Codex uses OpenAI-compatible API which requires the /v1 endpoint suffix.
The Universal Provider now automatically appends /v1 to base_url when
generating Codex provider config if not already present.

- Handle trailing slashes to avoid double slashes
- Apply fix to both backend (to_codex_provider) and frontend preview

* feat: auto-sync universal provider to apps on creation

Previously, users had to manually click sync after adding a universal
provider. Now it automatically syncs to Claude/Codex/Gemini on creation,
providing a smoother user experience.

---------

Co-authored-by: Jason <farion1231@gmail.com>

src-tauri/src/commands/provider.rs

@@ -229,3 +229,97 @@ pub fn update_providers_sort_order(
     let app_type = AppType::from_str(&app).map_err(|e| e.to_string())?;
     ProviderService::update_sort_order(state.inner(), app_type, updates).map_err(|e| e.to_string())
 }
+
+// ============================================================================
+// 统一供应商（Universal Provider）命令
+// ============================================================================
+
+use crate::provider::UniversalProvider;
+use std::collections::HashMap;
+use tauri::{AppHandle, Emitter};
+
+/// 统一供应商同步完成事件的 payload
+#[derive(Clone, serde::Serialize)]
+pub struct UniversalProviderSyncedEvent {
+    /// 操作类型: "upsert" | "delete" | "sync"
+    pub action: String,
+    /// 统一供应商 ID
+    pub id: String,
+}
+
+/// 发送统一供应商同步事件，通知前端刷新供应商列表
+fn emit_universal_provider_synced(app: &AppHandle, action: &str, id: &str) {
+    let _ = app.emit(
+        "universal-provider-synced",
+        UniversalProviderSyncedEvent {
+            action: action.to_string(),
+            id: id.to_string(),
+        },
+    );
+}
+
+/// 获取所有统一供应商
+#[tauri::command]
+pub fn get_universal_providers(
+    state: State<'_, AppState>,
+) -> Result<HashMap<String, UniversalProvider>, String> {
+    ProviderService::list_universal(state.inner()).map_err(|e| e.to_string())
+}
+
+/// 获取单个统一供应商
+#[tauri::command]
+pub fn get_universal_provider(
+    state: State<'_, AppState>,
+    id: String,
+) -> Result<Option<UniversalProvider>, String> {
+    ProviderService::get_universal(state.inner(), &id).map_err(|e| e.to_string())
+}
+
+/// 添加或更新统一供应商
+#[tauri::command]
+pub fn upsert_universal_provider(
+    app: AppHandle,
+    state: State<'_, AppState>,
+    provider: UniversalProvider,
+) -> Result<bool, String> {
+    let id = provider.id.clone();
+    let result =
+        ProviderService::upsert_universal(state.inner(), provider).map_err(|e| e.to_string())?;
+
+    // 发送事件通知前端刷新
+    emit_universal_provider_synced(&app, "upsert", &id);
+
+    Ok(result)
+}
+
+/// 删除统一供应商
+#[tauri::command]
+pub fn delete_universal_provider(
+    app: AppHandle,
+    state: State<'_, AppState>,
+    id: String,
+) -> Result<bool, String> {
+    let result =
+        ProviderService::delete_universal(state.inner(), &id).map_err(|e| e.to_string())?;
+
+    // 发送事件通知前端刷新
+    emit_universal_provider_synced(&app, "delete", &id);
+
+    Ok(result)
+}
+
+/// 同步统一供应商到各应用（手动触发）
+#[tauri::command]
+pub fn sync_universal_provider(
+    app: AppHandle,
+    state: State<'_, AppState>,
+    id: String,
+) -> Result<bool, String> {
+    let result =
+        ProviderService::sync_universal_to_apps(state.inner(), &id).map_err(|e| e.to_string())?;
+
+    // 发送事件通知前端刷新
+    emit_universal_provider_synced(&app, "sync", &id);
+
+    Ok(result)
+}