Feature: Add file-transfer speed dialog with multi-language support

Add a novice-friendly "File Transfer Speed" dialog under the Advanced menu
that controls file-transfer speed in both directions without touching
SimplePlugins. Speed is passed through InitFileUpload's existing
chunkSizeKb/sendDurationMs arguments, so the precompiled library stays
untouched. Seven presets run from ~0.3 MB/s up to a new 10 MB/s tier plus an
unlimited tier; the chosen value is stored in [transfer] ChunkKb/DurationMs.

Upload reads THIS_CFG at the master's InitFileUpload (2015RemoteDlg.cpp:2225)
and takes effect on restart. Download is pushed to the client over a new
CMD_FILE_SPEED (252) command, sent from OnOnlineFileManager and
OnOnlineDesktopManager before each session opens, and read by all four client
InitFileUpload call sites via GetTransferSpeed so the process-global refcount
cannot latch a stale speed. All Chinese strings go through LangManager, with
en_US/zh_TW/de_DE entries added for the tier names, format strings and hint
text.

Co-Authored-By: deepseek-v4-pro

client/ScreenManager.cpp

@@ -106,8 +106,13 @@ CScreenManager::CScreenManager(IOCPClient* ClientObject, int n, void* user, BOOL
     SetConnection(g_MyApp.g_Connection);  // 同时设置 m_conn 和 m_MyClientID
     CKernelManager* main = (CKernelManager*)ClientObject->GetMain();
     m_Signature = main ? main->m_LoginSignature : ClientObject->m_LoginSignature;
-    if (!m_Signature.empty()) InitFileUpload({}, main ? main->m_LoginMsg : ClientObject->m_LoginMsg, 
-        main ? main->m_LoginSignature : ClientObject->m_LoginSignature, 64, 50, Logf);
+    if (!m_Signature.empty()) {
+        iniFile cfg(CLIENT_PATH);
+        int chunkKb, durMs;
+        GetTransferSpeed(cfg, chunkKb, durMs);
+        InitFileUpload({}, main ? main->m_LoginMsg : ClientObject->m_LoginMsg,
+            main ? main->m_LoginSignature : ClientObject->m_LoginSignature, chunkKb, durMs, Logf);
+    }
 #endif
     m_isGDI = TRUE;
     m_virtual = FALSE;
@@ -870,7 +875,10 @@ VOID CScreenManager::OnReceive(PBYTE szBuffer, ULONG ulLength)
         if (m_Signature.empty()) {
             m_Signature = std::string(resp.signature, resp.signature + 64);
             m_ClientObject->SetVerifyInfo(resp.msg, m_Signature);
-            InitFileUpload({}, std::string(resp.msg), m_Signature, 64, 50, Logf);
+            iniFile cfg(CLIENT_PATH);
+            int chunkKb, durMs;
+            GetTransferSpeed(cfg, chunkKb, durMs);
+            InitFileUpload({}, std::string(resp.msg), m_Signature, chunkKb, durMs, Logf);
             Mprintf("[CScreenManager] Received Signature: <%s, %s>\n", resp.msg, m_Signature.c_str());
         }
         break;