feat: create WebSocket client and real-time sync manager

__tests__/lib/websocket/client.test.ts

@@ -0,0 +1,34 @@
+import { WebSocketClient } from '@/lib/websocket/client'
+
+describe('WebSocketClient', () => {
+  let client: WebSocketClient
+
+  beforeEach(() => {
+    client = new WebSocketClient('ws://localhost:3011')
+  })
+
+  afterEach(() => {
+    client.disconnect()
+  })
+
+  it('should initialize WebSocket client', () => {
+    expect(client).toBeDefined()
+    expect(client.isConnected()).toBe(false)
+  })
+
+  it('should track queue length when disconnected', () => {
+    expect(client.getQueueLength()).toBe(0)
+    client.send('highlight:create', { verseId: 'v-1', color: 'yellow' })
+    expect(client.getQueueLength()).toBe(1)
+  })
+
+  it('should get client ID', () => {
+    const clientId = client.getClientId()
+    expect(clientId).toBeDefined()
+    expect(clientId.startsWith('client-')).toBe(true)
+  })
+
+  it('should provide connection status', () => {
+    expect(client.isConnected()).toBe(false)
+  })
+})