fix(launcher): add missing ae_util import and format heartbeat datetime

- Resolved ReferenceError: ae_util is not defined.
- Formatted heartbeat to SQL-compatible datetime string.

src/routes/events/[event_id]/(launcher)/launcher_background_sync.svelte

@@ -7,6 +7,7 @@
     import { ae_loc, ae_api } from '$lib/stores/ae_stores';
     import { events_slct } from '$lib/stores/ae_events_stores';
     import { events_func } from '$lib/ae_events_functions';
+    import { ae_util } from '$lib/ae_utils/ae_utils';
     import { db_events } from '$lib/ae_events/db_events';
     import * as native from '$lib/electron/electron_relay';
 
@@ -147,7 +148,7 @@
             if (!info) return;
 
             const update_payload = {
-                heartbeat: new Date().toISOString(),
+                heartbeat: ae_util.iso_datetime_formatter(new Date(), 'datetime_iso'),
                 info_hostname: info.hostname,
                 info_ip_list: info.ip_addresses.join(', '),
                 meta_json: {