feat(01-08): enhance login page with comprehensive error handling

- Connected to AuthProvider for real authentication
- Added specific error messages for different exception types
- Implemented error message display with proper styling
- Added accessibility error announcements via Semantics
- Enhanced form validation with empty field checks
- Connected to real authentication flow instead of simulation
- Added error disposal when user starts typing
- Included loading state management

lib/features/authentication/presentation/pages/login_page.dart

@@ -1,24 +1,26 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 import '../widgets/auth_form.dart';
 import '../widgets/auth_button.dart';
+import '../../../../providers/auth_provider.dart';
+import '../../../../core/errors/auth_exceptions.dart';
 
 /// Login screen with email/password authentication
-class LoginPage extends StatefulWidget {
+class LoginPage extends ConsumerStatefulWidget {
   const LoginPage({super.key});
 
   @override
-  State<LoginPage> createState() => _LoginPageState();
+  ConsumerState<LoginPage> createState() => _LoginPageState();
 }
 
-class _LoginPageState extends State<LoginPage> {
+class _LoginPageState extends ConsumerState<LoginPage> {
   final _formKey = GlobalKey<FormState>();
   final _emailController = TextEditingController();
   final _passwordController = TextEditingController();
   
   bool _isLoading = false;
-  String? _emailError;
+  String? _errorMessage;
-  String? _passwordError;
 
   @override
   void dispose() {
@@ -79,19 +81,19 @@ class _LoginPageState extends State<LoginPage> {
                     email: _emailController.text,
                     onEmailChanged: (value) {
                       setState(() {
-                        _emailError = null;
+                        _errorMessage = null;
                         _emailController.text = value;
                       });
                     },
-                    emailError: _emailError,
+                    emailError: null,
                     password: _passwordController.text,
                     onPasswordChanged: (value) {
                       setState(() {
-                        _passwordError = null;
+                        _errorMessage = null;
                         _passwordController.text = value;
                       });
                     },
-                    passwordError: _passwordError,
+                    passwordError: null,
                     onSubmit: _handleLogin,
                     submitButtonText: 'Sign In',
                     isLoading: _isLoading,
@@ -99,6 +101,40 @@ class _LoginPageState extends State<LoginPage> {
 ),
                    const SizedBox(height: 16),
                    
+                   // Error message display
+                   if (_errorMessage != null) ...[
+                     Container(
+                       padding: const EdgeInsets.all(12),
+                       decoration: BoxDecoration(
+                         color: Theme.of(context).colorScheme.errorContainer,
+                         borderRadius: BorderRadius.circular(8),
+                         border: Border.all(
+                           color: Theme.of(context).colorScheme.error,
+                           width: 1,
+                         ),
+                       ),
+                       child: Row(
+                         children: [
+                           Icon(
+                             Icons.error_outline,
+                             size: 20,
+                             color: Theme.of(context).colorScheme.error,
+                           ),
+                           const SizedBox(width: 8),
+                           Expanded(
+                             child: Text(
+                               _errorMessage!,
+                               style: Theme.of(context).textTheme.bodyMedium?.copyWith(
+                                 color: Theme.of(context).colorScheme.onErrorContainer,
+                               ),
+                             ),
+                           ),
+                         ],
+                       ),
+                     ),
+                     const SizedBox(height: 16),
+                   ],
+                   
                    // Forgot password link
                   Align(
                     alignment: Alignment.centerRight,
@@ -149,8 +185,7 @@ class _LoginPageState extends State<LoginPage> {
   Future<void> _handleLogin() async {
     // Clear previous errors
     setState(() {
-      _emailError = null;
+      _errorMessage = null;
-      _passwordError = null;
     });
 
     // Validate form
@@ -158,32 +193,71 @@ class _LoginPageState extends State<LoginPage> {
       return;
     }
 
+    // Check for empty fields
+    final email = _emailController.text.trim();
+    final password = _passwordController.text;
+    
+    if (email.isEmpty || password.isEmpty) {
+      setState(() {
+        _errorMessage = 'Please enter both email and password';
+      });
+      return;
+    }
+
     // Show loading state
     setState(() {
       _isLoading = true;
     });
 
     try {
-      // TODO: Implement actual authentication logic
+      final authProvider = ref.read(authProvider.notifier);
-      // For now, simulate API call
+      await authProvider.signIn(email, password);
-      await Future.delayed(const Duration(seconds: 2));
       
-      // Simulate successful login
       if (mounted) {
         // Navigate to home or dashboard
         context.go('/home');
       }
     } catch (e) {
-      // Handle authentication errors
+      if (mounted) {
         setState(() {
           _isLoading = false;
-        
+          _errorMessage = _mapErrorToUserFriendlyMessage(e);
-        // TODO: Implement proper error handling
-        // For now, show generic error
-        _passwordError = 'Invalid email or password';
         });
+        
+        // Announce error for accessibility
+        _announceErrorForAccessibility(_errorMessage!);
       }
     }
+  }
+
+  /// Maps authentication exceptions to user-friendly error messages
+  String _mapErrorToUserFriendlyMessage(Object error) {
+    if (error is InvalidCredentialsException) {
+      return 'Invalid password. Please check your password and try again.';
+    } else if (error is UserNotFoundException) {
+      return 'Account not found. Please check your email address or sign up for a new account.';
+    } else if (error is NetworkException) {
+      return 'Network connection failed. Please check your internet connection and try again.';
+    } else if (error is SessionExpiredException) {
+      return 'Your session has expired. Please sign in again.';
+    } else if (error is EmailNotVerifiedException) {
+      return 'Please verify your email address before signing in. Check your inbox for verification email.';
+    } else if (error is AuthDisabledException) {
+      return 'Authentication is currently disabled. Please try again later.';
+    } else if (error is TooManyRequestsException) {
+      return 'Too many login attempts. Please wait a moment and try again.';
+    } else if (error is AuthException) {
+      return error.message;
+    } else {
+      return 'An unexpected error occurred. Please try again.';
+    }
+  }
+
+  /// Announces error message for screen readers
+  void _announceErrorForAccessibility(String errorMessage) {
+    // Use Semantics to announce the error for screen readers
+    SemanticsService.announce(errorMessage, TextDirection.ltr);
+  }
 
   void _handleForgotPassword() {
     // Navigate to password reset page