Notification Bell

Build a notification bell component in Angular. The component should:

1. Poll a REST API (GET /api/notifications/unread-count) every 30 seconds to get the number of unread notifications.
2. Display a bell icon with a badge showing the unread count. Hide the badge when the count is zero.
3. When clicked, open a dropdown that fetches the latest 10 notifications from GET /api/notifications?limit=10 and displays them as a list with title, message preview, and relative timestamp.
4. Handle API errors gracefully -- show a "Could not load notifications" message instead of breaking.

API Response Shapes

// GET /api/notifications/unread-count
{ "data": { "count": 3 } }

// GET /api/notifications?limit=10
{
  "data": [
    {
      "id": "n1",
      "title": "New comment",
      "preview": "Alice replied to your post...",
      "createdAt": "2025-12-01T10:30:00Z",
      "read": false
    }
  ]
}

Output

Produce TypeScript files in a src/app/ directory:

• src/app/notifications/notification.model.ts -- TypeScript type definitions
• src/app/notifications/notification.service.ts -- service handling both API calls
• src/app/notifications/notification-bell.component.ts -- the bell with badge and dropdown

Do not include test files or build configuration.