Remove _random ID references and fix hosted file download ID

- Fix download button to use hosted_file_id instead of id (which resolved
  to event_file_id via _process_generic_props, hitting the wrong endpoint)
- Fix Dexie file table query in event_file_obj_tbl_wrapper to use _id
  fields (the indexed ones) instead of _id_random variants
- Remove _random fields from properties_to_save in event, event_session
- Drop _id_random fallbacks from launcher device ID resolution and
  background sync heartbeat
- Clean up dead comments and old FA anchor in post edit component
- Update TODO__Agents.md: BGH section removed, CMSC/Axonius shows added,
  download button fix marked complete

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

src/lib/ae_events/ae_events__event.ts

@@ -787,7 +787,7 @@ export const properties_to_save = [
     'event_id',
     'code',
     'account_id',
-    'account_id_random',
+    // 'account_id_random',
     'conference',
     'type',
     'name',

src/lib/ae_events/ae_events__event_file.ts

@@ -359,7 +359,7 @@ export async function create_event_file_obj_from_hosted_file_async({
     });
 
     if (return_obj) return result;
-    return result?.event_file_id || result?.id || result?.event_file_id_random;
+    return result?.event_file_id || result?.id;
 }
 
 export async function delete_ae_obj_id__event_file({

src/lib/ae_events/ae_events__event_session.ts

@@ -836,12 +836,12 @@ export async function email_sign_in__event_session({
 export const properties_to_save = [
     'id',
     'event_session_id',
-    'event_session_id_random',
+    // 'event_session_id_random',
     'external_id',
     'code',
     'for_type',
     'for_id',
-    'for_id_random',
+    // 'for_id_random',
     'type_code',
     'event_id',
     'event_location_id',