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/routes/idaa/(idaa)/bb/ae_idaa_comp__post_obj_id_edit.svelte

@@ -595,15 +595,6 @@ $effect(() => {
                     {#each $idaa_slct.post_obj.linked_li_json as linked_obj, index (linked_obj.hosted_file_id ?? index)}
                         <span
                             class="flex flex-col items-center gap-1 rounded-lg border bg-white/50 p-1">
-                            <!-- <a
-                            href={linked_obj.url}
-                            target="_blank"
-                            class="badge badge-info variant-filled-info"
-                            >
-                            <span class="fas fa-paperclip m-1"></span>
-                            {linked_obj.filename}
-                            ({linked_obj.hosted_file_id})
-                        </a> -->
 
                             {#if $ae_loc.authenticated_access}
                                 {@const file_id =
@@ -650,8 +641,6 @@ $effect(() => {
                                                     return false;
                                                 }
 
-                                                // ae_promises[linked_obj.event_file_id] = handle_delete__event_file({event_file_id: linked_obj.event_file_id});
-
                                                 // First - Attempt to delete the hosted file
                                                 ae_promises.delete__linked_obj =
                                                     await core_func