feat: Linear-style UI redesign with improved mobile experience

Major changes:
- Redesign cabinet with Linear-style components and top navigation
- Replace detail modals with dedicated pages (users, broadcasts, email templates)
- Add email channel support for broadcasts
- Remove pull-to-refresh, improve drag-and-drop on touch devices
- Fix Telegram Mini App: fullscreen, back button, scroll restoration
- Unify admin pages color scheme to design system
- Mobile-first improvements: horizontal tabs for settings, better touch targets

src/components/TicketNotificationBell.tsx

@@ -241,7 +241,11 @@ export default function TicketNotificationBell({ isAdmin = false }: TicketNotifi
       {/* Bell button */}
       <button
         onClick={() => setIsOpen(!isOpen)}
-        className="relative rounded-xl border border-dark-700/50 bg-dark-800/50 p-2 text-dark-400 transition-all duration-200 hover:bg-dark-700 hover:text-accent-400"
+        className={`relative rounded-xl border p-2 transition-all duration-200 ${
+          isOpen
+            ? 'border-dark-600 bg-dark-700 text-accent-400'
+            : 'border-dark-700/50 bg-dark-800/50 text-dark-400 hover:bg-dark-700 hover:text-accent-400'
+        }`}
         title={t('notifications.ticketNotifications', 'Ticket notifications')}
       >
         <BellIcon />