feat(api): extend registration endpoints with dynamic fields and section preferences

- PublicRegistrationData now returns registration_fields (portal-visible only),
  form toggles, and available_tags for tag_picker fields
- Volunteer registration accepts field_values and section_preferences with
  festival_section_id, processed via existing services
- PortalMe eager-loads fieldValues and sectionPreferences
- Section preferences now use the proper relational table instead of custom_fields JSON

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

api/tests/Feature/Api/V1/PublicRegistrationDataTest.php

@@ -8,6 +8,8 @@ use App\Models\CrowdType;
 use App\Models\Event;
 use App\Models\FestivalSection;
 use App\Models\Organisation;
+use App\Models\PersonTag;
+use App\Models\RegistrationFormField;
 use App\Models\TimeSlot;
 use Illuminate\Foundation\Testing\RefreshDatabase;
 use Tests\TestCase;
@@ -199,4 +201,132 @@ class PublicRegistrationDataTest extends TestCase
             ->assertJsonCount(1, 'data.sections')
             ->assertJsonPath('data.sections.0.name', 'Bar');
     }
+
+    // ─── Registration Fields ───────────────────────────────────────────
+
+    public function test_registration_data_includes_registration_fields(): void
+    {
+        $event = Event::factory()->create([
+            'organisation_id' => $this->organisation->id,
+            'status' => 'registration_open',
+            'slug' => 'fields-event',
+        ]);
+
+        $field = RegistrationFormField::factory()->selectField()->create([
+            'event_id' => $event->id,
+            'is_portal_visible' => true,
+            'is_admin_only' => false,
+            'sort_order' => 0,
+        ]);
+
+        RegistrationFormField::factory()->textareaField()->create([
+            'event_id' => $event->id,
+            'is_portal_visible' => true,
+            'is_admin_only' => false,
+            'sort_order' => 1,
+        ]);
+
+        $response = $this->getJson('/api/v1/public/events/fields-event/registration-data');
+
+        $response->assertOk()
+            ->assertJsonCount(2, 'data.registration_fields')
+            ->assertJsonPath('data.registration_fields.0.slug', $field->slug)
+            ->assertJsonPath('data.registration_fields.0.field_type', 'select')
+            ->assertJsonPath('data.registration_fields.0.is_required', false);
+    }
+
+    public function test_registration_data_excludes_admin_only_fields(): void
+    {
+        $event = Event::factory()->create([
+            'organisation_id' => $this->organisation->id,
+            'status' => 'registration_open',
+            'slug' => 'admin-fields-event',
+        ]);
+
+        RegistrationFormField::factory()->create([
+            'event_id' => $event->id,
+            'label' => 'Public field',
+            'slug' => 'public-field',
+            'is_portal_visible' => true,
+            'is_admin_only' => false,
+        ]);
+
+        // Admin-only field (should be excluded)
+        RegistrationFormField::factory()->create([
+            'event_id' => $event->id,
+            'label' => 'Admin only field',
+            'slug' => 'admin-only-field',
+            'is_portal_visible' => true,
+            'is_admin_only' => true,
+        ]);
+
+        // Not portal visible (should be excluded)
+        RegistrationFormField::factory()->create([
+            'event_id' => $event->id,
+            'label' => 'Hidden field',
+            'slug' => 'hidden-field',
+            'is_portal_visible' => false,
+            'is_admin_only' => false,
+        ]);
+
+        $response = $this->getJson('/api/v1/public/events/admin-fields-event/registration-data');
+
+        $response->assertOk()
+            ->assertJsonCount(1, 'data.registration_fields')
+            ->assertJsonPath('data.registration_fields.0.slug', 'public-field');
+    }
+
+    public function test_registration_data_includes_form_toggles(): void
+    {
+        $event = Event::factory()->create([
+            'organisation_id' => $this->organisation->id,
+            'status' => 'registration_open',
+            'slug' => 'toggles-event',
+            'registration_show_section_preferences' => true,
+            'registration_show_availability' => false,
+        ]);
+
+        $response = $this->getJson('/api/v1/public/events/toggles-event/registration-data');
+
+        $response->assertOk()
+            ->assertJsonPath('data.event.registration_show_section_preferences', true)
+            ->assertJsonPath('data.event.registration_show_availability', false);
+    }
+
+    public function test_registration_data_includes_available_tags_for_tag_picker(): void
+    {
+        $event = Event::factory()->create([
+            'organisation_id' => $this->organisation->id,
+            'status' => 'registration_open',
+            'slug' => 'tags-event',
+        ]);
+
+        $tag = PersonTag::factory()->create([
+            'organisation_id' => $this->organisation->id,
+            'name' => 'EHBO',
+            'category' => 'Certificaat',
+            'is_active' => true,
+        ]);
+
+        PersonTag::factory()->create([
+            'organisation_id' => $this->organisation->id,
+            'name' => 'Barervaring',
+            'category' => 'Ervaring',
+            'is_active' => true,
+        ]);
+
+        RegistrationFormField::factory()->tagPickerField()->create([
+            'event_id' => $event->id,
+            'tag_category' => 'Certificaat',
+            'is_portal_visible' => true,
+            'is_admin_only' => false,
+        ]);
+
+        $response = $this->getJson('/api/v1/public/events/tags-event/registration-data');
+
+        $response->assertOk()
+            ->assertJsonCount(1, 'data.registration_fields')
+            ->assertJsonCount(1, 'data.registration_fields.0.available_tags')
+            ->assertJsonPath('data.registration_fields.0.available_tags.0.name', 'EHBO');
+    }
 }