单点或群聊发送消息不走Socket,看了再关

**Bug 描述**
对于客户端来说,相互间的通信都是基于socket的,它不应该关注消息转发的逻辑.

1.在这点上消息发送上不统一,职责也不太清晰.
2.如果将来改成真正的点对点通信,类似于局域网内部传输,这种转发模式很致命
3.客户端模块应该是独立的,毕竟应该是两个人之间通信(转发是内部逻辑,不应该暴露给客户端).

可以考虑客户端发送给socket服务器,收到后socket返回ack,由socket服务器向中控服务器发送转发请求,中控服务器收到后,发到处理队列,并发轮训处理队列,存储消息,查询转发服务器转发,或存入离线服务中.

No files, tests, or entry points are named; start by locating the client paths for single and group message sends and tracing their socket/server handling. Compare both paths with the proposed socket ACK, forwarding, queue, storage, and offline-service flow; done requires a decided scope and matching behavior.

Written by the indexing model from the issue text.