fix(web): ensure localStorage mock exists for tests

apps/web/vitest.setup.ts

@@ -24,3 +24,34 @@ Object.defineProperty(window, "matchMedia", {
     dispatchEvent: () => false,
   }),
 });
+
+// Ensure localStorage exists with a full Storage API for tests.
+if (!window.localStorage || typeof window.localStorage.clear !== "function") {
+  let store: Record<string, string> = {};
+  const storageMock: Storage = {
+    getItem: (key: string): string | null => store[key] ?? null,
+    setItem: (key: string, value: string): void => {
+      store[key] = value;
+    },
+    removeItem: (key: string): void => {
+      // eslint-disable-next-line @typescript-eslint/no-dynamic-delete
+      delete store[key];
+    },
+    clear: (): void => {
+      store = {};
+    },
+    get length(): number {
+      return Object.keys(store).length;
+    },
+    key: (index: number): string | null => {
+      const keys = Object.keys(store);
+      return keys[index] ?? null;
+    },
+  };
+
+  Object.defineProperty(window, "localStorage", {
+    value: storageMock,
+    writable: true,
+    configurable: true,
+  });
+}