feat: add official subscription quota display for Gemini

- Read Gemini OAuth credentials from macOS Keychain (gemini-cli-oauth)
  or legacy file (~/.gemini/oauth_creds.json)
- Auto-refresh expired access tokens using refresh_token (Google OAuth
  tokens expire in ~1h, unlike Claude/Codex)
- Two-step API: loadCodeAssist for project ID, then retrieveUserQuota
  for per-model quota buckets
- Classify models into Pro/Flash/Flash Lite categories, show min
  remaining fraction as utilization percentage
- Extend isOfficialProvider() for Gemini (no API key + no base URL)
- Parameterize expiredHint i18n key with tool name for all three apps

src/components/providers/ProviderCard.tsx

@@ -68,6 +68,15 @@ function isOfficialProvider(provider: Provider, appId: AppId): boolean {
     const apiKey = config?.auth?.OPENAI_API_KEY;
     return !apiKey || (typeof apiKey === "string" && apiKey.trim() === "");
   }
+  if (appId === "gemini") {
+    // 无 GEMINI_API_KEY 且无 GOOGLE_GEMINI_BASE_URL → Google OAuth 官方模式
+    const apiKey = config?.env?.GEMINI_API_KEY;
+    const baseUrl = config?.env?.GOOGLE_GEMINI_BASE_URL;
+    return (
+      (!apiKey || (typeof apiKey === "string" && apiKey.trim() === "")) &&
+      (!baseUrl || (typeof baseUrl === "string" && baseUrl.trim() === ""))
+    );
+  }
   return false;
 }