Fix mobile responsiveness across all pages

- BookingsPage: hide Номер/Выезд/Источник columns on small screens, show nights inline on mobile
- GuestsPage: stats grid 2→4 cols (grid-cols-2 lg:grid-cols-4), table columns hidden on mobile (md/lg breakpoints), GuestModal stats 2→4 cols on sm+
- BookingDetailPanel: full-width on mobile (w-full sm:w-[400px])
- Topbar: notifications panel full-width on mobile (w-[calc(100vw-1rem)] sm:w-96)
- LoyaltyPage, MaintenancePage, DiscountsPage, TariffsPage: stats grids grid-cols-2 lg:grid-cols-4

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/bookings/BookingDetailPanel.tsx

@@ -171,7 +171,7 @@ export function BookingDetailPanel({ booking, room, rooms, allBookings, onClose,
     <>
       <div className="fixed inset-0 z-40" onClick={onClose} />
 
-      <div className="fixed right-0 top-0 bottom-0 z-50 w-[400px] bg-white dark:bg-slate-800 border-l border-slate-200 dark:border-slate-700 shadow-2xl flex flex-col">
+      <div className="fixed right-0 top-0 bottom-0 z-50 w-full sm:w-[400px] bg-white dark:bg-slate-800 border-l border-slate-200 dark:border-slate-700 shadow-2xl flex flex-col">
 
         {/* Toast notification */}
         {toast && (