fix(geschichten-new): add request to makeEvent and vi.fn wrapper to createApiClient mock

Sentry's wrapLoadWithSentry reads event.request.method — the test's makeEvent
now provides a real Request object. createApiClient mock was a plain function;
wrapping with vi.fn() enables vi.mocked(...).mockReturnValue in individual tests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/geschichten/new/page.server.test.ts

@@ -5,9 +5,9 @@ vi.mock('$env/dynamic/private', () => ({
 }));
 
 vi.mock('$lib/shared/api.server', () => ({
-	createApiClient: () => ({
+	createApiClient: vi.fn(() => ({
 		GET: vi.fn().mockResolvedValue({ response: { ok: false }, data: null })
-	})
+	}))
 }));
 
 import { load } from './+page.server';
@@ -15,6 +15,7 @@ import { load } from './+page.server';
 function makeEvent(search: string, canBlogWrite = true) {
 	return {
 		url: new URL(`http://localhost/geschichten/new${search}`),
+		request: new Request(`http://localhost/geschichten/new${search}`),
 		fetch: vi.fn(),
 		parent: vi.fn().mockResolvedValue({ canBlogWrite })
 	} as never;