feat(gemini): add Gemini provider integration (#202)

* feat(gemini): add Gemini provider integration

- Add gemini_config.rs module for .env file parsing
- Extend AppType enum to support Gemini
- Implement GeminiConfigEditor and GeminiFormFields components
- Add GeminiIcon with standardized 1024x1024 viewBox
- Add Gemini provider presets configuration
- Update i18n translations for Gemini support
- Extend ProviderService and McpService for Gemini

* fix(gemini): resolve TypeScript errors, add i18n support, and fix MCP logic

**Critical Fixes:**
- Fix TS2741 errors in tests/msw/state.ts by adding missing Gemini type definitions
- Fix ProviderCard.extractApiUrl to support GOOGLE_GEMINI_BASE_URL display
- Add missing apps.gemini i18n keys (zh/en) for proper app name display
- Fix MCP service Gemini cross-app duplication logic to prevent self-copy

**Technical Details:**
- tests/msw/state.ts: Add gemini default providers, current ID, and MCP config
- ProviderCard.tsx: Check both ANTHROPIC_BASE_URL and GOOGLE_GEMINI_BASE_URL
- services/mcp.rs: Skip Gemini in sync_other_side logic with unreachable!() guards
- Run pnpm format to auto-fix code style issues

**Verification:**
- ✅ pnpm typecheck passes
- ✅ pnpm format completed

* feat(gemini): enhance authentication and config parsing

- Add strict and lenient .env parsing modes
- Implement PackyCode partner authentication detection
- Support Google OAuth official authentication
- Auto-configure security.auth.selectedType for PackyCode
- Add comprehensive test coverage for all auth types
- Update i18n for OAuth hints and Gemini config

---------

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

src/components/AppSwitcher.tsx

@@ -1,5 +1,5 @@
 import type { AppId } from "@/lib/api";
-import { ClaudeIcon, CodexIcon } from "./BrandIcons";
+import { ClaudeIcon, CodexIcon, GeminiIcon } from "./BrandIcons";
 
 interface AppSwitcherProps {
   activeApp: AppId;
@@ -46,6 +46,26 @@ export function AppSwitcher({ activeApp, onSwitch }: AppSwitcherProps) {
         <CodexIcon size={16} />
         <span>Codex</span>
       </button>
+
+      <button
+        type="button"
+        onClick={() => handleSwitch("gemini")}
+        className={`inline-flex items-center gap-2 px-3 py-2 rounded-md text-sm font-medium transition-all duration-200 ${
+          activeApp === "gemini"
+            ? "bg-white text-gray-900 shadow-sm dark:bg-gray-900 dark:text-gray-100 dark:shadow-none"
+            : "text-gray-500 hover:text-gray-900 hover:bg-white/50 dark:text-gray-400 dark:hover:text-gray-100 dark:hover:bg-gray-800/60"
+        }`}
+      >
+        <GeminiIcon
+          size={16}
+          className={
+            activeApp === "gemini"
+              ? "text-[#4285F4] dark:text-[#4285F4] transition-colors duration-200"
+              : "text-gray-500 dark:text-gray-400 group-hover:text-[#4285F4] dark:group-hover:text-[#4285F4] transition-colors duration-200"
+          }
+        />
+        <span>Gemini</span>
+      </button>
     </div>
   );
 }