refactor(web/test): default svelte-query mock in vitest.setup; remove from 34 files (B3)

web/vitest.setup.ts

@@ -1,9 +1,20 @@
 import '@testing-library/jest-dom/vitest';
-import { beforeEach, afterEach } from 'vitest';
+import { beforeEach, afterEach, vi } from 'vitest';
 import { render } from '@testing-library/svelte';
 import ToastHost from './src/lib/components/ToastHost.svelte';
 import { clearToast } from './src/lib/stores/toast.svelte';
 
+// Default svelte-query mock for the whole test suite. Most component
+// tests just need useQueryClient to return SOMETHING — they never assert
+// on the result. Tests that need to assert on invalidateQueries (named
+// mock pattern) override this with their own per-file vi.mock. The
+// override wins because per-file mocks take precedence over setup-file
+// mocks in vitest.
+vi.mock('@tanstack/svelte-query', async (orig) => {
+  const actual = (await orig()) as Record<string, unknown>;
+  return { ...actual, useQueryClient: () => ({ invalidateQueries: vi.fn() }) };
+});
+
 // Node 25 ships a partial localStorage global that lacks getItem/setItem/clear
 // unless launched with --localstorage-file. jsdom sees Node's global and skips
 // installing its own. Replace with an in-memory Storage-compatible polyfill so