fix(presence-service): JWT guard 向后兼容无 type 字段的旧 token

新 token 含 type:'access'，旧 token 无 type 字段。
改为：只有 type 字段存在且不为 'access' 时才拒绝，
避免已登录用户因旧 token 格式导致心跳永久 401。

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

backend/services/presence-service/src/shared/guards/jwt-auth.guard.ts

@@ -23,7 +23,8 @@ export class JwtAuthGuard implements CanActivate {
 
     try {
       const payload = await this.jwtService.verifyAsync(token);
-      if (payload.type !== 'access') throw new UnauthorizedException('无效的令牌类型');
+      // 兼容旧 token（无 type 字段）和新 token（type: 'access'）
+      if (payload.type && payload.type !== 'access') throw new UnauthorizedException('无效的令牌类型');
       request.user = {
         userId: payload.userId,
         accountSequence: payload.accountSequence,