Feature: Two-way remote chat (远程交谈)

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

client/ClientDll_vs2015.vcxproj

@@ -216,6 +216,7 @@
     <ClCompile Include="CFFmpegH264Encoder.cpp" />
     <ClCompile Include="EncoderFactory.cpp" />
     <ClCompile Include="TalkManager.cpp" />
+    <ClCompile Include="ChatManager.cpp" />
     <ClCompile Include="VideoManager.cpp" />
     <ClCompile Include="X264Encoder.cpp" />
   </ItemGroup>
@@ -270,6 +271,7 @@
     <ClInclude Include="StdAfx.h" />
     <ClInclude Include="SystemManager.h" />
     <ClInclude Include="TalkManager.h" />
+    <ClInclude Include="ChatManager.h" />
     <ClInclude Include="VideoCodec.h" />
     <ClInclude Include="VideoManager.h" />
     <ClInclude Include="X264Encoder.h" />