fix(state): prefs test localStorage mock typing

src/state/__tests__/prefs.test.ts

@@ -3,13 +3,13 @@ import { getPrefs, setPrefs } from '../prefs';
 
 describe('prefs', () => {
   beforeEach(() => {
+    const store: Record<string, string> = {};
     vi.stubGlobal('localStorage', {
-      store: {} as Record<string, string>,
       getItem(key: string) {
-        return this.store[key] ?? null;
+        return store[key] ?? null;
       },
       setItem(key: string, value: string) {
-        this.store[key] = value;
+        store[key] = value;
       },
     });
   });