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/CDlgFileSend.h

@@ -51,6 +51,14 @@ public:
     BOOL m_bTargetOffline = FALSE;   // C2C目标已离线，已发送取消包
     enum { IDD = IDD_DIALOG_FILESEND };
 
+    // 传输速度统计（用于标题实时显示速度，如 "发送文件 - 5.3M/s"）
+    CStringW  m_strBaseTitle;               // 标题基础部分（"发送文件"/"接收文件 (V2)" 等，Unicode），首帧进度时捕获
+    bool      m_bBaseTitleCaptured = false;
+    uint64_t  m_ullTotalBytes = 0;          // 累计传输字节
+    uint64_t  m_ullLastBytes = 0;
+    ULONGLONG m_ullLastTick = 0;            // 上次速度采样时刻 (ms)
+    double    m_dSpeedBps = 0.0;            // 平滑后的速度 (B/s)
+
 protected:
     virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV 支持
 
@@ -59,6 +67,8 @@ protected:
     afx_msg LRESULT OnUpdateFileProgress(WPARAM wParam, LPARAM lParam);
     afx_msg LRESULT OnFinishFileSend(WPARAM wParam, LPARAM lParam);
 
+    void UpdateTitleWithSpeed(uint64_t dataLength);  // 累计字节并周期性刷新标题速度
+
 public:
     CProgressCtrl m_Progress;
     virtual BOOL OnInitDialog();