Add pagination to the devices list screen

Mirror the notifications list paging pattern (offset/limit, fetch one
extra row to detect the next page, First/Prev/Next controls) across the
devices DB query, REST endpoint, API client and UI. Also add a First
page button to the notifications pagination row.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/lib/home/notifications_list.dart

@@ -234,6 +234,14 @@ class _NotificationsListState extends State<NotificationsList> {
         child: Row(
           mainAxisAlignment: MainAxisAlignment.center,
           children: [
+            IconButton.outlined(
+              onPressed: _currentPage > 0 && !_isLoading
+                  ? () => _fetchPage(0)
+                  : null,
+              icon: const Icon(Icons.first_page),
+              tooltip: 'First page',
+            ),
+            const SizedBox(width: 8),
             IconButton.outlined(
               onPressed: _currentPage > 0 && !_isLoading
                   ? () => _fetchPage(_currentPage - 1)