feat: add quit option

Author: vixalien

data/ui/layout/sidebar.blp

@@ -49,13 +49,13 @@ menu primary_menu {
     }
 
     item {
-      label: _("_Keyboard Shortcuts");
-      action: "win.show-help-overlay";
+      label: _("_About Muzika");
+      action: "app.about";
     }
 
     item {
-      label: _("_About Muzika");
-      action: "app.about";
+      label: _("_Quit");
+      action: "app.quit";
     }
   }
 }