Closing the client-side chat dialog (via the "end chat" button or the title-bar
X) now only hides the window and keeps the session alive, instead of destroying
it. Closing the chat stays server-initiated: the next message from the server
reopens the hidden dialog via the existing SW_RESTORE path in OnReceive, and the
dialog is only truly destroyed on COMMAND_CHAT_CLOSE or connection close.
Co-Authored-By: deepseek-v4-pro
Add a "远程交谈" toolbar button (placed after 连接管理) that sends COMMAND_CHAT(161) to the selected host. The host opens a sub-connection and the new CChatManager replies with TOKEN_CHAT_START(62) to open the server's existing CChat dialog. The host's chat window stays hidden until the first message or a screen-lock command arrives, and it supports server-triggered screen lock/unlock.
Co-Authored-By: deepseek-v4-pro
