fix: improve server connection handling during authentication

- Updated AuthStateManager to clear the active server ID upon logout, ensuring a proper return to the server connection page.
- Enhanced RouterNotifier to allow users to stay on the server connection page if authenticated, improving navigation flow.
- Modified AuthenticationPage to navigate back to the server connection page instead of popping the navigation stack, enhancing user experience during server setup.

lib/core/auth/auth_state_manager.dart

@@ -562,6 +562,10 @@ class AuthStateManager extends _$AuthStateManager {
       await storage.clearAuthData();
       _updateApiServiceToken(null);
 
+      // Clear active server to force return to server connection page
+      await storage.setActiveServerId(null);
+      ref.invalidate(activeServerProvider);
+
       // Update state
       _update(
         (current) => current.copyWith(
@@ -577,6 +581,10 @@ class AuthStateManager extends _$AuthStateManager {
     } catch (e) {
       DebugLogger.error('logout-failed', scope: 'auth/state', error: e);
       // Even if logout fails, clear local state
+      final storage = ref.read(optimizedStorageServiceProvider);
+      await storage.setActiveServerId(null);
+      ref.invalidate(activeServerProvider);
+
       _update(
         (current) => current.copyWith(
           status: AuthStatus.unauthenticated,