feat(tray): 实现 tray_init 完成 system tray selection 接管

src/backend/x11/tray.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <stdint.h>
+#include <xcb/xproto.h>
+
+#include "interface/tray.h"
+
+extern const tray_api_t tray_api;
+
+typedef struct backend_t backend_t;
+
+void tray_init(
+  backend_t *backend,
+  xcb_window_t host_window,
+  int32_t host_width,
+  int32_t host_height
+);