Feat: TLS certificate menu and config dialog for the MFC server

Add a "TLS证书" item to the Extensions menu below "MCP设置" that opens a
runtime-built dialog to enable one-way TLS and set the certificate and
private-key paths. On OK it writes the [tls] Enabled/CertPath/KeyPath keys
and calls ServerTlsIdentity::Load() so the change takes effect for new
connections immediately (design doc §7.1), mirroring the existing
CMcpSettingsDlg runtime-template pattern. All new strings are wired into
the en_US / zh_TW / de_DE language files, and the menu item is gated by
HIDE_MENU_TLS_CERTIFICATE / MF_TLS_CERTIFICATE like MCP settings.

Co-Authored-By: deepseek-v4-pro

server/2015Remote/lang/en_US.ini

@@ -2084,3 +2084,15 @@ JPEG
 连接数:%d=Connections: %d
 强制断开=Force Disconnect
 远程交谈=Talk
+
+; ===== TLS =====
+TLS证书(&T)...=TLS Certificate(&T)...
+TLS证书=TLS Certificate
+启用加密=Enable Encryption
+证书路径=Certificate Path
+私钥路径=Private Key Path
+请填写证书路径=Please specify the certificate path
+请填写私钥路径=Please specify the private key path
+TLS 配置已保存。=TLS settings saved.
+改动对新建连接即时生效。=Changes take effect immediately for new connections.
+证书/私钥加载失败，加密功能未生效。请检查文件路径与格式（证书 PEM、私钥 PKCS#8）。=Failed to load certificate/private key; encryption is not active. Check the file path and format (PEM certificate, PKCS#8 private key).