feat: implement Google OAuth support for Android and iOS

- Added support for Google OAuth with separate client IDs for Android and iOS.
- Updated `verify_google_id_token` to validate `aud` against both client IDs and check `email_verified`.
- Modified `google_oauth_handler` to accept and process the new client IDs.
- Enhanced security by enforcing explicit JWT algorithm validation.
- Updated mobile app to handle Google OAuth flow using `expo-auth-session`.
- Fixed API request to send `id_token` in snake_case as expected by the backend.
- Added necessary environment variables for Google client IDs in mobile app.
- Implemented intent filter for Google OAuth redirect in AndroidManifest.xml.

mobile/package.json

@@ -18,10 +18,13 @@
     "@react-navigation/native-stack": "^7.3.16",
     "axios": "^1.7.7",
     "expo": "~54.0.33",
+    "expo-auth-session": "~7.0.10",
     "expo-camera": "~17.0.10",
     "expo-constants": "~18.0.13",
+    "expo-crypto": "~15.0.8",
     "expo-file-system": "~19.0.21",
     "expo-font": "~14.0.11",
+    "expo-intent-launcher": "^55.0.8",
     "expo-linking": "~8.0.11",
     "expo-router": "~6.0.23",
     "expo-secure-store": "~15.0.8",
@@ -30,6 +33,7 @@
     "expo-sqlite": "~16.0.10",
     "expo-status-bar": "~3.0.9",
     "expo-system-ui": "~6.0.9",
+    "expo-web-browser": "~15.0.10",
     "react": "19.1.0",
     "react-dom": "19.1.0",
     "react-hook-form": "^7.53.0",