fix(app): cache useFavorites snapshot to prevent infinite re-render

app/app/hooks/use-favorites.ts

@@ -3,14 +3,20 @@ import { useCallback, useSyncExternalStore } from "react";
 const STORAGE_KEY = "favorites";
 
 let listeners: Array<() => void> = [];
+let cachedRaw: string | null = null;
+let cachedParsed: string[] = [];
 
 function getSnapshot(): string[] {
   try {
     const raw = localStorage.getItem(STORAGE_KEY);
-    return raw ? JSON.parse(raw) : [];
+    if (raw !== cachedRaw) {
+      cachedRaw = raw;
+      cachedParsed = raw ? JSON.parse(raw) : [];
+    }
   } catch {
-    return [];
+    cachedParsed = [];
   }
+  return cachedParsed;
 }
 
 function subscribe(cb: () => void) {
@@ -20,12 +26,18 @@ function subscribe(cb: () => void) {
   };
 }
 
+const EMPTY: string[] = [];
+function getServerSnapshot(): string[] {
+  return EMPTY;
+}
+
 function notify() {
+  cachedRaw = null;
   listeners.forEach((l) => l());
 }
 
 export function useFavorites() {
-  const favorites = useSyncExternalStore(subscribe, getSnapshot, () => []);
+  const favorites = useSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
 
   const isFavorite = useCallback(
     (id: string) => favorites.includes(id),