feat(form-builder): FORM-02 TAG_PICKER sync listener (ARCH §31.10)

Rebuilds the tag-sync flow purged in S2a, now listener-driven against the
universal FormBuilder (ARCH §31.10).

- SyncTagPickerSelectionsOnSubmit listener: ShouldQueue on connection=redis
  queue=default. Filters to event_registration + person subjects with at
  least one TAG_PICKER form_value. Logs on failure, never rethrows so
  sibling listeners keep running.
- AppServiceProvider registers the listener via Event::listen alongside
  the existing S1 observers.
- PersonIdentityService::confirmMatch now calls
  FormTagSyncService::rebuildForPerson after setting person.user_id — the
  deferred-sync path for persons who filled in TAG_PICKER fields before
  their account was linked.
- ARCH-FORM-BUILDER.md §31.10 rewritten with the authoritative contract
  block from this session. Header bumped to v1.2.1.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

api/app/Providers/AppServiceProvider.php

@@ -44,6 +44,8 @@ use App\Models\FormBuilder\FormValue;
 use App\Models\FormBuilder\FormValueOption;
 use App\Models\FormBuilder\FormWebhookDelivery;
 use App\Models\VolunteerAvailability;
+use App\Events\FormBuilder\FormSubmissionSubmitted;
+use App\Listeners\FormBuilder\SyncTagPickerSelectionsOnSubmit;
 use App\Observers\FormBuilder\FormValueObserver;
 use App\Observers\PersonObserver;
 use App\Observers\UserObserver;
@@ -122,6 +124,12 @@ class AppServiceProvider extends ServiceProvider
         User::observe(UserObserver::class);
         FormValue::observe(FormValueObserver::class);
 
+        // ARCH §31.10 — FORM-02 TAG_PICKER sync listener.
+        \Illuminate\Support\Facades\Event::listen(
+            FormSubmissionSubmitted::class,
+            SyncTagPickerSelectionsOnSubmit::class,
+        );
+
         ResetPassword::createUrlUsing(function ($user, string $token) {
             return config('crewli.portal_url') . '/wachtwoord-resetten?token=' . $token . '&email=' . urlencode($user->email);
         });