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/Controllers/Api/V1/RegistrationFieldTemplateController.php

@@ -0,0 +1,62 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Controllers\Api\V1;
+
+use App\Http\Controllers\Controller;
+use App\Http\Requests\Api\V1\StoreRegistrationFieldTemplateRequest;
+use App\Http\Requests\Api\V1\UpdateRegistrationFieldTemplateRequest;
+use App\Http\Resources\Api\V1\RegistrationFieldTemplateResource;
+use App\Models\Organisation;
+use App\Models\RegistrationFieldTemplate;
+use App\Services\RegistrationFieldTemplateService;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Resources\Json\AnonymousResourceCollection;
+use Illuminate\Support\Facades\Gate;
+
+final class RegistrationFieldTemplateController extends Controller
+{
+    public function __construct(
+        private readonly RegistrationFieldTemplateService $service,
+    ) {}
+
+    public function index(Organisation $organisation): AnonymousResourceCollection
+    {
+        Gate::authorize('viewAny', [RegistrationFieldTemplate::class, $organisation]);
+
+        $templates = $this->service->listForOrganisation($organisation);
+
+        return RegistrationFieldTemplateResource::collection($templates);
+    }
+
+    public function store(StoreRegistrationFieldTemplateRequest $request, Organisation $organisation): JsonResponse
+    {
+        Gate::authorize('create', [RegistrationFieldTemplate::class, $organisation]);
+
+        $template = $this->service->createTemplate($organisation, $request->validated());
+
+        return $this->created(new RegistrationFieldTemplateResource($template));
+    }
+
+    public function update(
+        UpdateRegistrationFieldTemplateRequest $request,
+        Organisation $organisation,
+        RegistrationFieldTemplate $registrationFieldTemplate,
+    ): JsonResponse {
+        Gate::authorize('update', [$registrationFieldTemplate, $organisation]);
+
+        $template = $this->service->updateTemplate($registrationFieldTemplate, $request->validated());
+
+        return $this->success(new RegistrationFieldTemplateResource($template));
+    }
+
+    public function destroy(Organisation $organisation, RegistrationFieldTemplate $registrationFieldTemplate): JsonResponse
+    {
+        Gate::authorize('delete', [$registrationFieldTemplate, $organisation]);
+
+        $this->service->deleteTemplate($registrationFieldTemplate);
+
+        return response()->json(null, 204);
+    }
+}