feat(01-06): create password update page with validation

- Implemented UpdatePasswordPage with password strength indicator
- Added password validation utility with comprehensive checks
- Enhanced AuthProvider with updatePasswordFromReset method
- Extended AuthRepository interface and implementation for password reset
- Added InvalidTokenException to auth exception hierarchy
- Includes accessibility features and error handling
- Password strength indicator with real-time feedback

Files:
- lib/features/authentication/presentation/pages/update_password_page.dart
- lib/core/utils/password_validator.dart
- lib/providers/auth_provider.dart
- lib/features/authentication/domain/repositories/auth_repository.dart
- lib/features/authentication/data/repositories/auth_repository_impl.dart
- lib/core/errors/auth_exceptions.dart

lib/features/authentication/data/repositories/auth_repository_impl.dart

@@ -302,6 +302,33 @@ class AuthRepositoryImpl implements AuthRepository {
     }
   }
 
+  @override
+  Future<void> updatePasswordFromReset(String newPassword) async {
+    try {
+      // Extract the current session to verify we have a valid reset token
+      final session = _supabase.auth.currentSession;
+      
+      if (session == null) {
+        throw const InvalidTokenException(
+          message: 'No valid password reset session found. Please request a new reset link.',
+          code: 'NO_RESET_SESSION',
+        );
+      }
+
+      // Update password using Supabase updateUser
+      await _supabase.auth.updateUser(
+        UserAttributes(
+          password: newPassword,
+        ),
+      );
+
+      // After successful password update, sign out to force re-authentication
+      await _supabase.auth.signOut();
+    } catch (e) {
+      throw AuthExceptionFactory.fromSupabaseError(e);
+    }
+  }
+
   /// Dispose of any active subscriptions
   /// 
   /// Call this when the repository is no longer needed to prevent memory leaks