test(server): suites record broadcasts on a FakeRealtimeService instead of mocking src/websocket

A hand-built service gets a FakeRealtimeService where it took a RealtimeService, a Nest testing module overrides the provider, and a suite over buildApp() spies on the container's instance (spyOnRealtime). The 167 vi.mock factories on src/websocket are gone, RealtimeService reads the socket registry in ws-state.ts directly, and the re-export stub src/websocket.ts is deleted. The facade's own suite now checks what reaches a socket instead of which module function it called.

server/tests/integration/auth.test.ts

@@ -17,7 +17,6 @@ vi.mock('../../src/db/database', async () => {
   const { createSnapshotTestDb, buildDbMock } = await import('../helpers/db-mock');
   return buildDbMock(createSnapshotTestDb());
 });
-vi.mock('../../src/websocket', () => ({ broadcast: vi.fn(), broadcastToUser: vi.fn() }));
 
 import { db as testDb } from '../../src/db/database';
 import { buildApp } from '../../src/bootstrap';