feat: fase 2 backend — crowd types, persons, sections, shifts, invite flow

- Crowd Types + Persons CRUD (73 tests)
- Festival Sections + Time Slots + Shifts CRUD met assign/claim flow (84 tests)
- Invite Flow + Member Management met InvitationService (109 tests)
- Schema v1.6 migraties volledig uitgevoerd
- DevSeeder bijgewerkt met crowd types voor testorganisatie

api/app/Models/CrowdList.php

@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Concerns\HasUlids;
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+
+final class CrowdList extends Model
+{
+    use HasFactory;
+    use HasUlids;
+
+    protected $fillable = [
+        'event_id',
+        'crowd_type_id',
+        'name',
+        'type',
+        'recipient_company_id',
+        'auto_approve',
+        'max_persons',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'auto_approve' => 'boolean',
+            'max_persons' => 'integer',
+        ];
+    }
+
+    public function event(): BelongsTo
+    {
+        return $this->belongsTo(Event::class);
+    }
+
+    public function crowdType(): BelongsTo
+    {
+        return $this->belongsTo(CrowdType::class);
+    }
+
+    public function recipientCompany(): BelongsTo
+    {
+        return $this->belongsTo(Company::class, 'recipient_company_id');
+    }
+
+    public function persons(): BelongsToMany
+    {
+        return $this->belongsToMany(Person::class, 'crowd_list_persons')
+            ->withPivot('added_at', 'added_by_user_id');
+    }
+}