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/providers/auth_provider.dart

@@ -393,6 +393,28 @@ class AuthProvider extends StateNotifier<AuthState> {
     }
   }
 
+  /// Updates password from reset token (password reset flow)
+  /// 
+  /// [newPassword] - The new password to set
+  /// 
+  /// Throws AuthException if update fails
+  Future<void> updatePasswordFromReset(String newPassword) async {
+    if (state.isLoading) return;
+
+    state = state.copyWith(isLoading: true, clearError: true);
+
+    try {
+      await _authRepository.updatePasswordFromReset(newPassword);
+      state = state.copyWith(isLoading: false);
+    } catch (e) {
+      state = state.copyWith(
+        isLoading: false,
+        error: e.toString(),
+      );
+      rethrow;
+    }
+  }
+
   /// Clears any authentication error
   void clearError() {
     state = state.copyWith(clearError: true);