revert(badges): remove _random workaround on badge create template ID

Per V3 convention, {obj_type}_id IS the random string — send
event_badge_template_id (not _random). The backend not saving it is
a backend bug, not a frontend concern.

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

src/routes/events/[event_id]/(badges)/badges/ae_comp__badge_create_form.svelte

@@ -118,9 +118,7 @@ async function handle_submit(event: Event) {
     try {
         const badge_data: key_val = {
             event_person_id,
-            // selected_template_id holds the random string (IDB stores _random overwritten into _id
-            // by _process_generic_props). The backend resolves _random fields to the integer FK.
-            event_badge_template_id_random: selected_template_id || null,
+            event_badge_template_id: selected_template_id || null,
             given_name,
             family_name,
             email: email || null,