fix: use Combobox for notification group selection in settings page

Settings page used a plain number input for ip_change_notification_group_id,
requiring users to manually enter a group ID. Replace it with a searchable
Combobox component (consistent with alert-rule/service/cron pages) and wrap
the settings route with NotificationProvider to load notification group data.

Closes nezhahq/nezha#1174

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

src/main.tsx

@@ -128,7 +128,11 @@ const router = createBrowserRouter([
             },
             {
                 path: "/dashboard/settings",
-                element: <SettingsPage />,
+                element: (
+                    <NotificationProvider withNotifierGroup>
+                        <SettingsPage />
+                    </NotificationProvider>
+                ),
             },
             {
                 path: "/dashboard/settings/user",