feat(auth): Enhance logout flow with comprehensive data clearing

lib/core/auth/api_auth_interceptor.dart

@@ -174,7 +174,6 @@ class ApiAuthInterceptor extends Interceptor {
 
   /// Clear auth token and notify callbacks
   /// Note: This should only be called for explicit logout, not for connection errors
-
   void _clearAuthToken() {
     _authToken = null;
     final future = onTokenInvalidated?.call();

lib/core/auth/auth_cache_manager.dart

@@ -100,11 +100,11 @@ class AuthCacheManager {
     DebugLogger.storage('Cache entry cleared: $key');
   }
 
-  /// Clear all auth-related cache
+  /// Clear all auth-related cache including server configs
   void clearAuthCache() {
     _cache.clear();
     _cacheTimestamps.clear();
-    DebugLogger.storage('All auth cache cleared');
+    DebugLogger.storage('All auth cache cleared (including server configs and custom headers)');
   }
 
   /// Clear expired cache entries

lib/core/auth/auth_state_manager.dart

@@ -677,7 +677,7 @@ class AuthStateManager extends _$AuthStateManager {
     }
   }
 
-  /// Logout user
+  /// Logout user and clear all data including server configs and custom headers
   Future<void> logout() async {
     _update(
       (current) =>
@@ -699,14 +699,20 @@ class AuthStateManager extends _$AuthStateManager {
         }
       }
 
-      // Clear all local auth data
+      // Clear all local auth data (including server configs with custom headers)
       final storage = ref.read(optimizedStorageServiceProvider);
       await storage.clearAuthData();
       _updateApiServiceToken(null);
 
       // Clear active server to force return to server connection page
       await storage.setActiveServerId(null);
+      
+      // Invalidate all auth-related providers to clear cached data
       ref.invalidate(activeServerProvider);
+      ref.invalidate(serverConfigsProvider);
+      
+      // Clear auth cache manager
+      _cacheManager.clearAuthCache();
 
       // Update state
       _update(
@@ -719,7 +725,7 @@ class AuthStateManager extends _$AuthStateManager {
         ),
       );
 
-      DebugLogger.auth('Logout complete');
+      DebugLogger.auth('Logout complete - all data cleared including server configs and custom headers');
     } catch (e, stack) {
       DebugLogger.error(
         'logout-failed',
@@ -729,8 +735,19 @@ class AuthStateManager extends _$AuthStateManager {
       );
       // Even if logout fails, clear local state where possible
       final storage = ref.read(optimizedStorageServiceProvider);
+      try {
+        await storage.clearAuthData();
+      } catch (clearError) {
+        DebugLogger.error(
+          'logout-clear-failed',
+          scope: 'auth/state',
+          error: clearError,
+        );
+      }
       await storage.setActiveServerId(null);
       ref.invalidate(activeServerProvider);
+      ref.invalidate(serverConfigsProvider);
+      _cacheManager.clearAuthCache();
 
       _update(
         (current) => current.copyWith(
@@ -739,8 +756,8 @@ class AuthStateManager extends _$AuthStateManager {
           clearToken: true,
           clearUser: true,
           error:
-              'Logout error: $e. Secure credentials may remain stored; '
-              'please clear them from your device keychain.',
+              'Logout error: $e. Some data may remain stored; '
+              'please clear app data from your device settings if needed.',
         ),
       );
       _updateApiServiceToken(null);

lib/core/services/optimized_storage_service.dart

@@ -395,11 +395,15 @@ class OptimizedStorageService {
   // ---------------------------------------------------------------------------
   // Batch operations
   // ---------------------------------------------------------------------------
+  /// Clear all authentication-related data including credentials, tokens,
+  /// server configurations, and custom headers
   Future<void> clearAuthData() async {
     await Future.wait([
       deleteAuthToken(),
       deleteSavedCredentials(),
       _preferencesBox.delete(_activeServerIdKey),
+      // Clear server configurations (which include custom headers)
+      _secureCredentialStorage.clearAll(),
     ]);
 
     _cache.removeWhere(
@@ -416,7 +420,7 @@ class OptimizedStorageService {
     );
 
     DebugLogger.log(
-      'Auth data cleared in batch operation',
+      'Auth data cleared in batch operation (including server configs and custom headers)',
       scope: 'storage/optimized',
     );
   }

lib/core/services/secure_credential_storage.dart

@@ -280,11 +280,12 @@ class SecureCredentialStorage {
     }
   }
 
-  /// Clear all secure data
+  /// Clear all secure data including credentials, tokens, and server configurations
+  /// (which contain custom headers)
   Future<void> clearAll() async {
     try {
       await _secureStorage.deleteAll();
-      DebugLogger.storage('clear-ok', scope: 'credentials');
+      DebugLogger.storage('clear-ok (all secure data including server configs with custom headers)', scope: 'credentials');
     } catch (e) {
       DebugLogger.error('clear-failed', scope: 'credentials', error: e);
     }

lib/features/auth/views/connection_issue_page.dart

@@ -12,6 +12,7 @@ import '../../../core/widgets/error_boundary.dart';
 import '../../../l10n/app_localizations.dart';
 import '../../../shared/theme/theme_extensions.dart';
 import '../../../shared/widgets/conduit_components.dart';
+import '../../../shared/widgets/themed_dialogs.dart';
 import '../providers/unified_auth_providers.dart';
 
 class ConnectionIssuePage extends ConsumerStatefulWidget {
@@ -248,6 +249,18 @@ class _ConnectionIssuePageState extends ConsumerState<ConnectionIssuePage> {
   }
 
   Future<void> _logout(AppLocalizations l10n) async {
+    // Show confirmation dialog before logging out
+    final confirm = await ThemedDialogs.confirm(
+      context,
+      title: l10n.signOut,
+      message: l10n.endYourSession,
+      confirmText: l10n.signOut,
+      isDestructive: true,
+    );
+
+    if (!mounted) return;
+    if (!confirm) return;
+
     setState(() {
       _isLoggingOut = true;
       _statusMessage = null;