add start/business unit

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

@@ -115,15 +115,12 @@ class _LoginPageState extends ConsumerState<LoginPage> {
     }
   }
 
-  /// Navigate to register page
+  /// Navigate to business unit selection (registration flow)
   void _navigateToRegister() {
-    // TODO: Navigate to register page when route is set up
-    // context.go('/register');
-    ScaffoldMessenger.of(context).showSnackBar(
-      const SnackBar(
-        content: Text('Chức năng đăng ký đang được phát triển'),
-        behavior: SnackBarBehavior.floating,
-      ),
+    // Navigate to business unit selection page first
+    context.pushNamed(
+      RouteNames.businessUnitSelection,
+      extra: {'isRegistrationFlow': true},
     );
   }