fix: v2.0.4+24 — login fixes, signup toggle, forgot-password, guest SnackBar, Google OAuth

- Google Sign-In: wire serverClientId (639347358523-mtkm...apps.googleusercontent.com) so idToken is returned on Android
- Email login: raise timeout 10s→25s, add single retry on SocketException/TimeoutException
- Forgot Password: real glassmorphism bottom sheet with safe-degrade SnackBar (endpoint missing on backend)
- Create Account: same-page AnimatedSwitcher toggle with glassmorphism signup form; delete old RegisterScreen
- Desktop parity: DesktopLoginScreen same-page toggle; delete DesktopRegisterScreen
- Guest mode: remove ScaffoldMessenger SnackBar from HomeScreen outer catch (inner _safe wrappers already return [])
- LoginScreen: clearSnackBars() on postFrameCallback to prevent carried-over SnackBars from prior screens
- ProGuard: add Google Sign-In + OkHttp keep rules
- Version bump: 2.0.0+20 → 2.0.4+24; settings _appVersion → 2.0.4

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/features/auth/services/auth_service.dart

@@ -12,6 +12,13 @@ import '../models/user_model.dart';
 class AuthService {
   final ApiClient _api = ApiClient();
 
+  /// Google OAuth 2.0 Web Client ID from Google Cloud Console.
+  /// Must match the `GOOGLE_CLIENT_ID` env var set on the Django backend
+  /// so the server can verify the `id_token` audience.
+  /// Source: Google Cloud Console → APIs & Services → Credentials → Web application.
+  static const String _googleWebClientId =
+      '639347358523-mtkm3i8vssuhsun80rp2llt09eou0p8g.apps.googleusercontent.com';
+
   /// LOGIN → returns UserModel
   Future<UserModel> login(String username, String password) async {
     try {
@@ -158,7 +165,10 @@ class AuthService {
   /// GOOGLE OAUTH LOGIN → returns UserModel
   Future<UserModel> googleLogin() async {
     try {
-      final googleSignIn = GoogleSignIn(scopes: ['email']);
+      final googleSignIn = GoogleSignIn(
+        scopes: const ['email', 'profile'],
+        serverClientId: _googleWebClientId,
+      );
       final account = await googleSignIn.signIn();
       if (account == null) throw Exception('Google sign-in cancelled');
 
@@ -215,6 +225,16 @@ class AuthService {
     }
   }
 
+  /// FORGOT PASSWORD → backend sends reset instructions by email.
+  /// Frontend never leaks whether the email is registered — same UX on success and 404.
+  Future<void> forgotPassword(String email) async {
+    await _api.post(
+      ApiEndpoints.forgotPassword,
+      body: {'email': email},
+      requiresAuth: false,
+    );
+  }
+
   /// Logout – clear auth token and current_email (keep per-account display_name entries so they persist)
   Future<void> logout() async {
     try {