feat(portal): multi-step volunteer registration form with public event endpoint

- Add GET /api/v1/public/events/{slug}/registration-data endpoint for fetching
  event sections and time slots without auth
- Create 5-step registration form: personal info, details, motivation, section
  preferences, availability
- VeeValidate + Zod validation per step with Dutch error messages
- Auth-aware: pre-fills name/email for authenticated users
- Mobile responsive with custom chip-based step indicator
- Success page with contextual actions (dashboard vs login)
- Types, composable (TanStack Query), and Zod schemas

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

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

@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Feature\Api\V1;
+
+use App\Models\CrowdType;
+use App\Models\Event;
+use App\Models\FestivalSection;
+use App\Models\Organisation;
+use App\Models\TimeSlot;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class PublicRegistrationDataTest extends TestCase
+{
+    use RefreshDatabase;
+
+    private Organisation $organisation;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->organisation = Organisation::factory()->create();
+    }
+
+    public function test_returns_registration_data_for_open_event(): void
+    {
+        $event = Event::factory()->create([
+            'organisation_id' => $this->organisation->id,
+            'status' => 'registration_open',
+            'slug' => 'test-event-2026',
+        ]);
+
+        $section = FestivalSection::factory()->create([
+            'event_id' => $event->id,
+            'type' => 'standard',
+        ]);
+
+        FestivalSection::factory()->create([
+            'event_id' => $event->id,
+            'type' => 'cross_event',
+        ]);
+
+        $timeSlot = TimeSlot::factory()->create([
+            'event_id' => $event->id,
+            'person_type' => 'VOLUNTEER',
+        ]);
+
+        TimeSlot::factory()->create([
+            'event_id' => $event->id,
+            'person_type' => 'CREW',
+        ]);
+
+        $response = $this->getJson('/api/v1/public/events/test-event-2026/registration-data');
+
+        $response->assertOk()
+            ->assertJsonPath('data.event.id', $event->id)
+            ->assertJsonPath('data.event.name', $event->name)
+            ->assertJsonCount(1, 'data.sections')
+            ->assertJsonPath('data.sections.0.id', $section->id)
+            ->assertJsonCount(1, 'data.time_slots')
+            ->assertJsonPath('data.time_slots.0.id', $timeSlot->id);
+    }
+
+    public function test_returns_404_for_non_registration_open_event(): void
+    {
+        Event::factory()->create([
+            'organisation_id' => $this->organisation->id,
+            'status' => 'draft',
+            'slug' => 'draft-event',
+        ]);
+
+        $response = $this->getJson('/api/v1/public/events/draft-event/registration-data');
+
+        $response->assertNotFound();
+    }
+
+    public function test_returns_404_for_nonexistent_slug(): void
+    {
+        $response = $this->getJson('/api/v1/public/events/does-not-exist/registration-data');
+
+        $response->assertNotFound();
+    }
+}