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/FestivalSection.php

@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Builder;
+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\HasMany;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+final class FestivalSection extends Model
+{
+    use HasFactory;
+    use HasUlids;
+    use SoftDeletes;
+
+    protected $fillable = [
+        'event_id',
+        'name',
+        'type',
+        'sort_order',
+        'crew_need',
+        'crew_auto_accepts',
+        'crew_invited_to_events',
+        'added_to_timeline',
+        'responder_self_checkin',
+        'crew_accreditation_level',
+        'public_form_accreditation_level',
+        'timed_accreditations',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'crew_auto_accepts' => 'boolean',
+            'crew_invited_to_events' => 'boolean',
+            'added_to_timeline' => 'boolean',
+            'responder_self_checkin' => 'boolean',
+            'timed_accreditations' => 'boolean',
+        ];
+    }
+
+    public function event(): BelongsTo
+    {
+        return $this->belongsTo(Event::class);
+    }
+
+    public function shifts(): HasMany
+    {
+        return $this->hasMany(Shift::class);
+    }
+
+    public function scopeOrdered(Builder $query): Builder
+    {
+        return $query->orderBy('sort_order');
+    }
+}