feat: 实现前端认证系统，WebSocket 连接携带 JWT token

- 新增 AuthContext/AuthProvider：登录/注册状态管理，JWT 自动刷新
- 新增 AuthPage 组件：登录/注册表单，支持模式切换和前端校验
- 新增 api.ts：封装 auth REST API 客户端（register/login/refresh/logout）
- WebSocket 连接时拼接 ?token=<jwt>，重连自动携带
- useVisionSession 接受 accessToken 参数并透传
- App.tsx 包裹 AuthProvider，未登录时显示登录页
- storage.ts 新增 token/user 的 localStorage 存储
- i18n 新增中/英/日三语 auth 翻译
- App.css 新增 auth 页面和用户 badge 样式

frontend/src/lib/websocket.ts

@@ -24,6 +24,7 @@ export class CamTalkWebSocket {
   private reconnectAttempt = 0;
   private reconnectTimer: ReturnType<typeof setTimeout> | null = null;
   private shouldReconnect = true;
+  private token: string | undefined;
 
   private messageHandlers = new Set<MessageHandler>();
   private statusHandlers = new Set<StatusHandler>();
@@ -45,14 +46,16 @@ export class CamTalkWebSocket {
     return () => this.statusHandlers.delete(handler);
   }
 
-  /** 建立连接 */
-  connect(): void {
+  /** 建立连接，可选传入 JWT token 用于认证 */
+  connect(token?: string): void {
     if (this.ws?.readyState === WebSocket.OPEN) return;
 
+    this.token = token;
     this.shouldReconnect = true;
     this.setStatus("connecting");
 
-    const ws = new WebSocket(WS_URL);
+    const url = token ? `${WS_URL}?token=${encodeURIComponent(token)}` : WS_URL;
+    const ws = new WebSocket(url);
 
     ws.onopen = () => {
       this.reconnectAttempt = 0;
@@ -130,7 +133,7 @@ export class CamTalkWebSocket {
 
     this.reconnectTimer = setTimeout(() => {
       this.reconnectAttempt++;
-      this.connect();
+      this.connect(this.token);
     }, totalDelay);
   }