fix: stop the notification-permission toast from stacking

AppContent was declared inline inside App(), making it a new component
reference on every App render -- React would unmount/remount it each
time, re-running its useEffect (generateToken + FCM listener setup) and
re-showing the "Enable notifications" toast, which never auto-dismisses
and has no dedup, so they piled up. Moved AppContent to a stable
top-level component and added a one-per-tab guard on the toast itself
as a second line of defense.

src/App.js

@@ -13,14 +13,10 @@ import useInactivityLogout from 'hooks/useInactivityLogout';
 
 // ==============================|| APP - THEME, ROUTER, LOCAL  ||============================== //
 
-const App = () => {
-  const navigate = useNavigate();
-  useEffect(() => {
-    if (!localStorage.getItem('authname')) {
-      navigate('/login');
-    }
-  }, [navigate]);
-
+// Was previously declared inline inside App(), which made it a fresh
+// component reference on every App render — React would unmount/remount it
+// each time, re-firing its useEffect (and the FCM permission toast) on
+// every App re-render instead of once per app load.
 const AppContent = () => {
   useInactivityLogout();
 
@@ -37,6 +33,14 @@ const App = () => {
   );
 };
 
+const App = () => {
+  const navigate = useNavigate();
+  useEffect(() => {
+    if (!localStorage.getItem('authname')) {
+      navigate('/login');
+    }
+  }, [navigate]);
+
   return (
     <>
       <ThemeCustomization>

src/firebase_notification/notification.js

@@ -22,6 +22,12 @@ const opentoast = (message, color, vertical = 'bottom') => {
   });
 };
 
+// Notification.requestPermission() re-resolves with the browser's current
+// (often already-decided) permission every time this runs. Without a guard,
+// any repeat call — e.g. from a remount — re-shows the same permanent,
+// non-auto-dismissing toast and they stack up. Only warn once per tab.
+let notificationWarningShown = false;
+
 // ===================== Generate FCM Token =====================
 export const generateToken = async () => {
   try {
@@ -29,7 +35,10 @@ export const generateToken = async () => {
     dispatch(setFcmPermission(permission));
 
     if (permission !== 'granted') {
+      if (!notificationWarningShown) {
+        notificationWarningShown = true;
         opentoast('Enable notifications to receive OTP, alerts, and updates', 'error');
+      }
       return;
     }