Feature: Show live transfer speed in file-transfer dialog title

Add a smoothed bytes-per-second readout to the CDlgFileSend title,
refreshed about every 200 ms during transfer (e.g. "发送文件 - 5.3M/s").
The base title is captured on the first progress frame and the speed
suffix applied through Unicode APIs (GetWindowTextW / SetWindowTextW),
so the whole title stays correct on non-Chinese systems where the ANSI
message path would misdecode GBK as the system ACP.

Also add the missing "接收文件 (V2)" translation (en_US "Receive File (V2)",
zh_TW "接收檔案 (V2)"), so the V2 receive title no longer falls back to
raw Chinese on non-Chinese systems.

Co-Authored-By: deepseek-v4-pro

server/2015Remote/lang/en_US.ini

@@ -1400,6 +1400,7 @@ RDP
 C2C 文件传输=C2C File Transfer
 续传文件 (V2)=Resume File Upload (V2)
 发送文件 (V2)=Send File (V2)
+接收文件 (V2)=Receive File (V2)
 发送文件(%d/%d): %.2f%%=Send Files(%d/%d): %.2f%%
 接收文件(%d/%d): %.2f%%=Recv Files(%d/%d): %.2f%%
 [远程右键复制, 本地 Ctrl+V 粘贴]= [Remote Right-click Copy, Local Ctrl+V Paste]