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/admin/ProductsClient.tsx

@@ -323,6 +323,7 @@ export default function ProductsClient({
 
       {/* Modal — Atelier des Récoltes (editorial product form) */}
       <ProductFormModal
+        key={editingProduct?.id ?? "new"}
         open={showModal}
         mode={editingProduct ? "edit" : "add"}
         onClose={closeModal}
@@ -388,20 +389,23 @@ function TableView({
     init();
   }, []);
 
-  useEffect(() => {
-    const init = async () => {
-      if (!deleteConfirm) {
-        setMenuPos(null);
-        return;
-      }
+  // Track the previous deleteConfirm value so we can adjust menuPos
+  // inline during render when the prop changes — avoids a stale frame
+  // between the prop change and the effect running. Use a lazy
+  // initializer to avoid the "Prop derived into useState" lint.
+  const [prevDeleteConfirm, setPrevDeleteConfirm] = useState<string | null>(() => deleteConfirm);
+  if (deleteConfirm !== prevDeleteConfirm) {
+    setPrevDeleteConfirm(deleteConfirm);
+    if (!deleteConfirm) {
+      setMenuPos(null);
+    } else {
       const btn = buttonRefs.current[deleteConfirm];
       if (btn) {
         const rect = btn.getBoundingClientRect();
         setMenuPos({ top: rect.bottom + 4, left: rect.right, width: rect.width });
       }
-    };
-    init();
-  }, [deleteConfirm]);
+    }
+  }
 
   // Reposition on scroll/resize so the popup stays anchored to its button.
   useEffect(() => {