Feat: Per-client TLS transport toggle (TLS column + remote enable/disable)

Add a per-client TLS transport toggle controlled from the server, using the
presence of the client's trust-anchor certificate in the registry as the
single source of truth (no separate tls_enable flag).

- Client reports its TLS status via a new RES_TLS token (cert present -> 1)
  appended to LOGIN_INFOR's reserved field.
- Server online list gains a "TLS" column after the permission column.
- The "experimental features" right-click menu gains "TLS传输" / "取消TLS"
  with confirmation and a guard that prompts (instead of sending) when the
  server has no TLS certificate ready.
- New COMMAND_TLS_ENABLE / COMMAND_TLS_DISABLE (166/167): the server pushes
  its cert PEM into the client registry settings\tls_cert (enable) or deletes
  it (disable). The client picks this up on next startup via the existing
  ReadTrustAnchor logic, so the switch is non-live by design.
- Icons and en_US/zh_TW/de_DE translations for the new menu items.

Co-Authored-By: deepseek-v4-pro

common/commands.h

@@ -325,6 +325,8 @@ enum {
     COMMAND_FILE_MANAGER_PLUGIN = 163,   // 服务端 → 客户端：打开插件文件管理对话框（SimplePlugins 迁移）
     COMMAND_PRIVATE_SCREEN_PLUGIN = 164, // 服务端 → 客户端：打开隐私屏幕（虚拟桌面，SimplePlugins 迁移）
     COMMAND_DRAWING_BOARD_PLUGIN = 165,  // 服务端 → 客户端：打开远程画板（SimplePlugins 迁移）
+    COMMAND_TLS_ENABLE = 166,   // 服务端 → 客户端：启用 TLS 传输（写注册表，下次启动生效）
+    COMMAND_TLS_DISABLE = 167,  // 服务端 → 客户端：停用 TLS 传输（写注册表，下次启动生效）
 
     TOKEN_DECRYPT = 199,
     TOKEN_REGEDIT = 200,            // 注册表
@@ -1061,6 +1063,7 @@ enum LOGIN_RES {
     RES_CLIENT_ID = 16,                     // 客户端唯一ID
     RES_PID = 17,                           // 进程ID
     RES_FILESIZE = 18,                       // 文件大小
+    RES_TLS = 19,                           // TLS 传输启用标志 0/1
     RES_MAX,
 };