Fix: Deliver file-transfer speed via MasterSettings (was CMD_FILE_SPEED)

The file-transfer speed dialog previously sent a separate CMD_FILE_SPEED
(5 bytes) back-to-back before COMMAND_SCREEN_SPY / COMMAND_LIST_DRIVE when
opening remote desktop or file manager. The IOCP send path batches two
consecutive Send2Client calls into one WSASend of the accumulated
OutCompressedBuffer, so the client received the [FILE_SPEED][SCREEN_SPY]
command stream twice - the root cause of two remote-desktop dialogs popping
up on a single click (introduced in commit 76decec).

Fold the two values into MasterSettings (TransferChunkKb / TransferDurationMs,
uint16 each, before Reserved, sizeof unchanged at 1000) so they reach every
client on login and are broadcast to online clients when the dialog saves.
The client persists them into [transfer] on CMD_MASTERSETTING, guarded by
TransferChunkKb != 0 so older masters keep local defaults. CMD_FILE_SPEED(252)
and its client handler remain for backward compatibility, but the master no
longer sends it.

Update the design doc, the three GBK lang files' prompt entry, and the READMEs.

Co-Authored-By: deepseek-v4-pro

server/2015Remote/2015RemoteDlg.cpp

@@ -2425,6 +2425,12 @@ BOOL CMy2015RemoteDlg::OnInitDialog()
     strcpy(m_settings.GetPluginUrl, THIS_CFG.GetStr("settings", "GetPluginUrl", BRAND_URL_GET_PLUGIN).c_str());
     m_settings.Authorized = !pwd.empty() && !THIS_CFG.GetStr("settings", "PwdHmac").empty();
     m_settings.IsTrail = IsTrail(pwd);
+    {
+        int chunkKb, durMs;
+        GetTransferSpeed(THIS_CFG, chunkKb, durMs);
+        m_settings.TransferChunkKb    = (uint16_t)chunkKb;
+        m_settings.TransferDurationMs = (uint16_t)durMs;
+    }
     m_bEnableFileV2 = THIS_CFG.GetInt("settings", "EnableFileV2", 0) != 0;
 
     // 缩略图配置：从 [thumbnail] 节读取（独立于 MasterSettings，纯主控端 UI 偏好）。
@@ -4770,9 +4776,6 @@ VOID CMy2015RemoteDlg::OnOnlineDesktopManager()
 {
     if (!ShouldRemoteControl())
         return;
-    // 先下发当前文件传输速度档位，再开远程桌面：避免被控端 ScreenManager 先初始化
-    // 文件上传模块（进程级引用计数）把速度锁成旧值。
-    SendFileSpeedCommand();
     int n = THIS_CFG.GetInt("settings", "DXGI");
     BOOL all = THIS_CFG.GetInt("settings", "MultiScreen", TRUE);
     CString algo = THIS_CFG.GetStr("settings", "ScreenCompress", ALGORITHM_NULL).c_str();
@@ -4782,9 +4785,6 @@ VOID CMy2015RemoteDlg::OnOnlineDesktopManager()
 
 VOID CMy2015RemoteDlg::OnOnlineFileManager()
 {
-    // 先下发文件传输速度档位，再发 COMMAND_LIST_DRIVE 开文件管理：保证被控端
-    // CFileManager 构造时读到的 [transfer] 配置已是最新值。
-    SendFileSpeedCommand();
     BYTE	bToken = COMMAND_LIST_DRIVE;
     SendSelectedCommand(&bToken, sizeof(BYTE));
 }
@@ -9363,26 +9363,14 @@ void CMy2015RemoteDlg::OnFileTransferSpeed()
     if (dlg.DoModal() == IDOK) {
         THIS_CFG.SetInt("transfer", "ChunkKb", dlg.GetChunkKb());
         THIS_CFG.SetInt("transfer", "DurationMs", dlg.GetDurMs());
-        MessageBoxL("文件传输速度已保存。上传速度重启主控端后生效；下载速度下次打开文件管理或远程桌面后生效。",
+        m_settings.TransferChunkKb    = (uint16_t)dlg.GetChunkKb();
+        m_settings.TransferDurationMs = (uint16_t)dlg.GetDurMs();
+        SendMasterSettings(nullptr, m_settings);  // 下载速度随 MasterSettings 推送给在线客户端
+        MessageBoxL("文件传输速度已保存。上传速度重启主控端后生效；下载速度已推送到在线客户端，新连接的主机也会自动获取。",
                     "提示", MB_ICONINFORMATION);
     }
 }
 
-void CMy2015RemoteDlg::SendFileSpeedCommand()
-{
-    int chunkKb, durMs;
-    GetTransferSpeed(THIS_CFG, chunkKb, durMs);
-
-    // [cmd:1][chunkKb:uint16 LE][durationMs:uint16 LE]
-    BYTE buf[5];
-    buf[0] = CMD_FILE_SPEED;
-    buf[1] = (BYTE)(chunkKb & 0xFF);
-    buf[2] = (BYTE)((chunkKb >> 8) & 0xFF);
-    buf[3] = (BYTE)(durMs & 0xFF);
-    buf[4] = (BYTE)((durMs >> 8) & 0xFF);
-    SendSelectedCommand(buf, sizeof(buf));
-}
-
 void CMy2015RemoteDlg::ApplyThumbnailSettings()
 {
     // 任何已缓存的 HBITMAP 都是按"旧 ThumbWidth"渲染的，尺寸不再可信 —— 一律清空。