refactor: update styling and color classes across components

- Changed error message styling in ICalImportModal to use new color classes.
- Updated task completion styling in TaskListView to use new success color classes.
- Modified selected styling in ContactListItem tests to reflect new background class.
- Adjusted duplicate warning styling in ContactImportDialog to use new warning color classes.
- Refactored background and border colors in CalendarInvitationBanner for various statuses.
- Updated email list item and viewer components to use new warning and success color classes.
- Refined styling for unread indicators in email components.
- Enhanced error fallback styling in error components to use new warning color classes.
- Updated filter rule modal button hover styles to use new destructive color classes.
- Added experimental feature descriptions in Plugins and Themes settings.
- Refined vacation settings validation warning styling to use new warning color classes.
- Updated toast component styles to use new color classes for different states.
- Introduced a new built-in theme 'Qui' with specific color variables.
- Adjusted email security status colors to use new warning color classes.

components/calendar/calendar-day-view.tsx

@@ -182,7 +182,7 @@ export function CalendarDayView({
                         className={cn(
                           "flex-shrink-0 w-3.5 h-3.5 rounded-full border flex items-center justify-center",
                           isCompleted
-                            ? "bg-green-500 border-green-500 text-white"
+                            ? "bg-success border-success text-success-foreground"
                             : "border-muted-foreground/40 hover:border-primary"
                         )}
                       >
@@ -288,8 +288,8 @@ export function CalendarDayView({
                 style={{ top: (nowMinutes / 60) * HOUR_HEIGHT }}
               >
                 <div className="flex items-center">
-                  <div className="w-2.5 h-2.5 rounded-full bg-red-500 -ml-1" />
-                  <div className="flex-1 h-px bg-red-500" />
+                  <div className="w-2.5 h-2.5 rounded-full bg-destructive -ml-1" />
+                  <div className="flex-1 h-px bg-destructive" />
                 </div>
               </div>
             )}