fix: improve auth guard and resolve blank page issue

components/Layout.tsx

@@ -30,8 +30,8 @@ export const Layout: React.FC<{ children: React.ReactNode }> = ({ children }) =>
     const fetchCurrentUser = async () => {
       const storedUserId = localStorage.getItem('ctms_user_id');
       
-      if (!storedUserId) {
-        navigate('/login');
+      if (!storedUserId || storedUserId === 'undefined' || storedUserId === 'null') {
+        navigate('/login', { replace: true });
         return;
       }
 
@@ -42,11 +42,13 @@ export const Layout: React.FC<{ children: React.ReactNode }> = ({ children }) =>
         } else {
           // User ID exists in storage but not in DB (deleted user?)
           localStorage.removeItem('ctms_user_id');
-          navigate('/login');
+          localStorage.removeItem('ctms_tenant_id');
+          navigate('/login', { replace: true });
         }
       } catch (err) {
         console.error("Failed to fetch user:", err);
-        // Fallback or error state
+        // If API fails completely, we might want to allow offline mode or retry
+        // For now, let's just log it.
       }
     };
     fetchCurrentUser();
@@ -55,13 +57,15 @@ export const Layout: React.FC<{ children: React.ReactNode }> = ({ children }) =>
   const handleLogout = () => {
     localStorage.removeItem('ctms_user_id');
     localStorage.removeItem('ctms_tenant_id');
-    navigate('/login');
+    navigate('/login', { replace: true });
   };
 
   if (!currentUser) {
     const storedUserId = localStorage.getItem('ctms_user_id');
-    if (!storedUserId) return null; // Will redirect in useEffect
-    return <div className="flex h-screen items-center justify-center bg-slate-50 text-slate-400">Autenticando...</div>;
+    const isValid = storedUserId && storedUserId !== 'undefined' && storedUserId !== 'null';
+    
+    if (!isValid) return null; 
+    return <div className="flex h-screen items-center justify-center bg-slate-50 text-slate-400 font-medium">Iniciando sessão...</div>;
   }
 
   const isSuperAdmin = currentUser.role === 'super_admin';