Mock Worker globally and import vi in test mock helpers

happy-dom does not provide Worker, which breaks tests that import
composables using web workers (filter, selectMany). Add a MockWorker
to the global vitest setup mirroring the existing BroadcastChannel
mock.

The two test mock helpers (filter.ts, selectMany.ts) called
`vi.mock` without importing `vi`. With `globals: false` in
vitest.config.mts that throws ReferenceError. Import `vi`
explicitly.

Author: dannon

client/src/components/Form/Elements/FormSelectMany/worker/__mocks__/selectMany.ts

@@ -1,9 +1,9 @@
+import { vi } from "vitest";
 import { reactive, ref, watch } from "vue";
 
 import type { SelectOption, useSelectMany as UseSelectMany } from "../selectMany";
 import { main } from "../selectManyMain";
 
-// @ts-ignore - vi is a Vitest global
 vi.mock("@/components/Form/Elements/FormSelectMany/worker/selectMany", () => ({
     useSelectMany,
 }));

client/src/composables/__mocks__/filter.ts

@@ -1,9 +1,9 @@
 import { toValue } from "@vueuse/core";
+import { vi } from "vitest";
 import { computed, type Ref } from "vue";
 
 import type { useFilterObjectArray as UseFilterObjectArray } from "@/composables/filter";
 
-// @ts-ignore - vi is a Vitest global
 vi.mock("@/composables/filter", () => ({
     useFilterObjectArray,
 }));

client/tests/vitest/setup.ts

@@ -99,6 +99,32 @@ Object.defineProperty(global, "BroadcastChannel", {
     value: MockBroadcastChannel,
 });
 
+// Mock Worker so components using web workers (e.g. useFilterObjectArray)
+// don't throw "Worker is not defined" under happy-dom.
+class MockWorker extends EventTarget {
+    onmessage: ((event: MessageEvent) => void) | null = null;
+    onerror: ((event: ErrorEvent) => void) | null = null;
+    onmessageerror: ((event: MessageEvent) => void) | null = null;
+
+    constructor(_url: string | URL, _options?: WorkerOptions) {
+        super();
+    }
+
+    postMessage(_message: unknown) {
+        // No-op for tests
+    }
+
+    terminate() {
+        // No-op for tests
+    }
+}
+
+Object.defineProperty(global, "Worker", {
+    writable: true,
+    configurable: true,
+    value: MockWorker,
+});
+
 // Fail tests that log console errors or warnings
 // Replaces jest-fail-on-console functionality
 const failOnConsole = (await import("vitest-fail-on-console")).default;