Add maintenance severity levels, notifications context, and widget payment step

- HousekeepingPage: 3-level severity for maintenance reports (Не срочно / Средняя / Экстренно!); Экстренно automatically blocks the room and triggers an urgent notification; severity displayed as colored badge on task card
- NotificationsContext: extract shared notifications state from Topbar into context so any page can push notifications; add 'maintenance' type with wrench icon
- Topbar: migrate to NotificationsContext; add maintenance notification type with red Wrench icon
- BookingWidgetPage: add payment step after guest form when payment provider is connected (card number/expiry/CVV/name form); Без оплаты mode skips payment and shows "pay on site" message; hourly services (unit='ч') show date + time-from/time-to picker in form step

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

src/App.tsx

@@ -3,6 +3,7 @@ import { ThemeProvider } from './contexts/ThemeContext'
 import { AuthProvider } from './contexts/AuthContext'
 import { ModulesProvider } from './contexts/ModulesContext'
 import { AmenitiesProvider } from './contexts/AmenitiesContext'
+import { NotificationsProvider } from './contexts/NotificationsContext'
 import { AppLayout } from './layouts/AppLayout'
 import { LoginPage } from './pages/LoginPage'
 import { CalendarPage } from './pages/CalendarPage'
@@ -39,6 +40,7 @@ export default function App() {
     <ThemeProvider>
       <AuthProvider>
         <ModulesProvider>
+          <NotificationsProvider>
           <AmenitiesProvider>
           <BrowserRouter>
             <Routes>
@@ -89,6 +91,7 @@ export default function App() {
             </Routes>
           </BrowserRouter>
           </AmenitiesProvider>
+          </NotificationsProvider>
         </ModulesProvider>
       </AuthProvider>
     </ThemeProvider>