fix: react-doctor → 64/100 (Bugs 122, Perf 286, A11y 613, Maint 436)

- CartContext: lazy initializers replace mount-only useEffect
  hydration; remove 8 no-initialize-state warnings
- Toast/AdminSearchInput: React 19 useContext/use + drop
  forwardRef (3 no-react19-deprecated-apis)
- ProductFormModal: lazy initializers + useSyncExternalStore
  for mount; parent adds key=editingProduct.id
- InstallPrompt: useReducer for prompt state (no-cascading-set-state)
- QRScanModal: ref-based latest-callback pattern replaces
  useEffectEvent deps mistake
- OnboardingFlow: functional setState (rerender-functional-setstate)
- UsersPage/StopsCalendar/FeaturesAndStats: lazy initializers
  (rerender-lazy-state-init)
- FAQClientPage: server-side brand settings fetch via getBrandSettingsPublic
  in layout; remove supabase import
- LandingPageWrapper: href='#' → href='#top' (anchor-is-valid)
- TuxedoVideoHero: replace animate-bounce with ease-out-expo
  (no-inline-bounce-easing)
- ProductTableClient: useCallback for handleDeleted
  (jsx-no-new-function-as-prop)
- excel-parser: pre-compile delimiter regexes (js-hoist-regexp)
- water-log/settings: Promise.all for parallel DB calls
  (async-parallel)
- ToastNotification: extract toast store to separate file
  (only-export-components)
- WholesaleClient: inline <WholesaleIcon/> instead of hoisting to
  const (rendering-hoist-jsx)

src/components/notifications/InAppNotificationCenter.tsx

@@ -43,15 +43,9 @@ export default function NotificationCenter({ brandId, userId }: NotificationCent
     }
   }, [brandId]);
 
-  // Fetch notifications when opened
-  useEffect(() => {
-    const init = async () => {
-      if (isOpen && brandId) {
-        await fetchNotifications();
-      }
-    };
-    init();
-  }, [isOpen, brandId, fetchNotifications]);
+  // Fetch notifications when opened — handled in the click handler so
+  // we don't need a useEffect to watch `isOpen` and re-fetch on every
+  // open transition. See handleToggleOpen below.
 
   // Close on click outside
   useEffect(() => {
@@ -122,11 +116,19 @@ export default function NotificationCenter({ brandId, userId }: NotificationCent
     }
   };
 
+  const handleToggleOpen = useCallback(async () => {
+    const next = !isOpen;
+    setIsOpen(next);
+    if (next && brandId) {
+      await fetchNotifications();
+    }
+  }, [isOpen, brandId, fetchNotifications]);
+
   return (
     <div className="relative" ref={dropdownRef}>
       {/* Bell Icon Button */}
       <button type="button"
-        onClick={() => setIsOpen(!isOpen)}
+        onClick={handleToggleOpen}
         className="relative p-2 hover:bg-gray-100 rounded-xl transition-colors"
         aria-label={`Notifications ${unreadCount > 0 ? `(${unreadCount} unread)` : ""}`}
       >