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/lib/api/index.ts

@@ -1,5 +1,5 @@
 export type { AppId } from "./types";
-export { providersApi } from "./providers";
+export { providersApi, universalProvidersApi } from "./providers";
 export { settingsApi } from "./settings";
 export { mcpApi } from "./mcp";
 export { promptsApi } from "./prompts";

src/lib/api/providers.ts

@@ -1,6 +1,10 @@
 import { invoke } from "@tauri-apps/api/core";
 import { listen, type UnlistenFn } from "@tauri-apps/api/event";
-import type { Provider } from "@/types";
+import type {
+  Provider,
+  UniversalProvider,
+  UniversalProvidersMap,
+} from "@/types";
 import type { AppId } from "./types";
 
 export interface ProviderSortUpdate {
@@ -62,3 +66,44 @@ export const providersApi = {
     });
   },
 };
+
+// ============================================================================
+// 统一供应商（Universal Provider）API
+// ============================================================================
+
+export const universalProvidersApi = {
+  /**
+   * 获取所有统一供应商
+   */
+  async getAll(): Promise<UniversalProvidersMap> {
+    return await invoke("get_universal_providers");
+  },
+
+  /**
+   * 获取单个统一供应商
+   */
+  async get(id: string): Promise<UniversalProvider | null> {
+    return await invoke("get_universal_provider", { id });
+  },
+
+  /**
+   * 添加或更新统一供应商
+   */
+  async upsert(provider: UniversalProvider): Promise<boolean> {
+    return await invoke("upsert_universal_provider", { provider });
+  },
+
+  /**
+   * 删除统一供应商
+   */
+  async delete(id: string): Promise<boolean> {
+    return await invoke("delete_universal_provider", { id });
+  },
+
+  /**
+   * 手动同步统一供应商到各应用
+   */
+  async sync(id: string): Promise<boolean> {
+    return await invoke("sync_universal_provider", { id });
+  },
+};