Add JettingProxy relay, convert Xpl2Client to active connection modelHEADmaster

Insert a transparent TCP proxy between the controller and N clients:
- JettingProxy listens on 9110-9112 (controller) and 9210-9212 (clients)
- Broadcasts controller frames to all clients, forwards client→controller
- Independent KA_PING handling on both sides

Convert Xpl2Client from passive QTcpServer listener to active QTcpSocket
outbound connections with auto-retry. New QML API: host/commandPort
properties, connectToProxy()/disconnectFromProxy() replacing
startListening()/stopListening().

1 files changed, 1 insertions, 0 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a81bd5f..7c8fe3a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -31,5 +31,6 @@ add_subdirectory(src)
 
 if(PROJECT_IS_TOP_LEVEL)
   add_subdirectory(jetting-interface)
+  add_subdirectory(jetting-proxy)
   add_subdirectory(mock-jetting-controller)
 endif()