Enhance accessibility and improve form semantics across multiple pages

- Added `htmlFor` attributes to labels for better accessibility in Calendar, Dashboard, GuestJoin, Login, Register, RoomDetail, and Settings pages.
- Included `aria-hidden` attributes for icons to improve screen reader experience.
- Set `autoComplete` attributes for input fields to enhance user experience during form filling.
- Implemented `role` and `aria` attributes for radio groups and buttons to improve accessibility compliance.

src/components/NotificationBell.jsx

@@ -83,6 +83,11 @@ export default function NotificationBell() {
       <button
         onClick={() => setOpen(prev => !prev)}
         className="relative p-2 rounded-lg hover:bg-th-hover text-th-text-s transition-colors"
+        aria-label={unreadCount > 0
+          ? `${t('notifications.bell')} (${unreadCount})`
+          : t('notifications.bell')}
+        aria-haspopup="true"
+        aria-expanded={open}
         title={t('notifications.bell')}
       >
         <Bell size={20} />
@@ -174,6 +179,7 @@ export default function NotificationBell() {
                       <button
                         onClick={(e) => handleDelete(e, n.id)}
                         className="opacity-0 group-hover:opacity-100 p-0.5 rounded-sm hover:text-th-error transition-all text-th-text-s/50"
+                        aria-label={t('notifications.delete')}
                         title={t('notifications.delete')}
                       >
                         <X size={13} />