feat: registration form fields, section preferences, tag sync & schema updates

Implement EAV system for dynamic event-specific registration fields
with organisation-level templates, person section preferences with
priority ranking, and TagSyncService for deferred tag_picker sync.

New tables: registration_field_templates, registration_form_fields,
person_field_values, person_section_preferences.
New columns: persons.remarks, events.registration_show_section_preferences,
events.registration_show_availability.

58 tests, 126 assertions — all 432 tests pass (zero regressions).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/app/Http/Resources/Api/V1/PersonFieldValueResource.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Resources\Api\V1;
+
+use App\Enums\RegistrationFieldType;
+use App\Models\PersonTag;
+use Illuminate\Http\Request;
+use Illuminate\Http\Resources\Json\JsonResource;
+
+final class PersonFieldValueResource extends JsonResource
+{
+    public function toArray(Request $request): array
+    {
+        $field = $this->registrationFormField;
+
+        return [
+            'field_slug' => $field?->slug,
+            'field_label' => $field?->label,
+            'field_type' => $field?->field_type?->value,
+            'value' => $this->value,
+            'selected_options' => $this->selected_options,
+            'tag_names' => $this->when(
+                $field?->field_type === RegistrationFieldType::TAG_PICKER && !empty($this->selected_options),
+                function () {
+                    return PersonTag::whereIn('id', $this->selected_options ?? [])
+                        ->pluck('name')
+                        ->all();
+                }
+            ),
+        ];
+    }
+}