✨ feat(ui): add NotificationPopup and related styles for displaying system notifications

main.css

@@ -9,6 +9,7 @@
 @import url("./styles/launcher.css");
 @import url("./styles/kanban.css");
 @import url("./styles/calendar.css");
+@import url("./styles/notification.css");
 
 * {
   all: unset;