refactor: rebuild desktop client with Slint

src/gui/platform/tray/linux_tray.h

@@ -10,6 +10,7 @@
 #if defined(__linux__) && !defined(__APPLE__)
 
 #include <cstdint>
+#include <functional>
 #include <memory>
 #include <string>
 
@@ -23,6 +24,9 @@ class LinuxTray {
  public:
   LinuxTray(::SDL_Window* app_window, const std::string& tooltip,
             int language_index, uint32_t exit_event_type);
+  LinuxTray(std::function<void()> show_window,
+            std::function<void()> hide_window, std::function<void()> exit_app,
+            const std::string& tooltip, int language_index);
   ~LinuxTray();
 
   bool MinimizeToTray();