[FIX] wayland: restrict setAsFrameless to Wayland only

Prevent unconditional frameless calls on non-Wayland platforms.

Signed-off-by: Texas0295 <kimura@texas0295.top>

lib/main.dart

@@ -130,7 +130,6 @@ void main() async {
           debugPrint('[Wayland] setAsFrameless failed: $e');
         }
       }
-      await windowManager.setAsFrameless();
       await windowManager.setMinimumSize(defaultSize);
       await windowManager.show();
       await windowManager.focus();