feat(timetable): factories + ArtistTimetableDevSeeder

Eight factories with named states (Genre, Artist, ArtistContact, Stage,
ArtistEngagement, Performance, AdvanceSection, AdvanceSubmission).

ArtistTimetableDevSeeder hooked into DevSeeder::seedEchtFeesten after
the form-builder showcase. Produces:
- 4 stages (Mainstage, Havana, Stairway, Socialite) with prototype-style
  hex colours
- 4 stages × 3 sub-events = 12 stage_days rows
- 4 genres (Hardstyle, Techno, Indie, Live band)
- 6 master artists, each with one tour-manager ArtistContact
- 12 engagements with status mix (1 Draft, 2 Requested, 3 Option,
  2 Confirmed, 3 Contracted, 1 Cancelled). Two artists have two
  engagements each (different sub-events) — exercises D17 multi-
  engagement-per-artist.
- 13 performances, including one parked (stage_id=null = wachtrij)
  and one B2B pair within 3 minutes on Mainstage Saturday to seed
  the Session 4 frontend B2B detector.

Also fix LogOptions method name across 8 models: dontSubmitEmptyLogs()
→ dontLogEmptyChanges() (Spatie's actual API; surfaced when DevSeeder
ran).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

api/database/factories/ArtistFactory.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Database\Factories;
+
+use App\Models\Artist;
+use App\Models\Company;
+use App\Models\Genre;
+use App\Models\Organisation;
+use Illuminate\Database\Eloquent\Factories\Factory;
+use Illuminate\Support\Str;
+
+/** @extends Factory<Artist> */
+final class ArtistFactory extends Factory
+{
+    /** @return array<string, mixed> */
+    public function definition(): array
+    {
+        $name = fake()->unique()->company().' '.fake()->randomElement(['Live', 'Sound', 'Project', 'Collective', 'DJ Set']);
+
+        return [
+            'organisation_id' => Organisation::factory(),
+            'name' => $name,
+            'slug' => Str::slug($name).'-'.Str::lower(Str::random(4)),
+            'default_genre_id' => null,
+            'default_draw' => fake()->numberBetween(50, 5000),
+            'star_rating' => fake()->numberBetween(1, 5),
+            'home_base_country' => fake()->randomElement(['NL', 'BE', 'DE', 'FR', 'UK']),
+            'agent_company_id' => null,
+            'notes' => null,
+        ];
+    }
+
+    public function withGenre(?Genre $genre = null): static
+    {
+        return $this->state(function (array $attrs) use ($genre): array {
+            $resolved = $genre ?? Genre::factory()->create([
+                'organisation_id' => $attrs['organisation_id'],
+            ]);
+
+            return ['default_genre_id' => $resolved->id];
+        });
+    }
+
+    public function withAgent(?Company $company = null): static
+    {
+        return $this->state(function (array $attrs) use ($company): array {
+            $resolved = $company ?? Company::factory()->create([
+                'organisation_id' => $attrs['organisation_id'],
+                'type' => 'agency',
+            ]);
+
+            return ['agent_company_id' => $resolved->id];
+        });
+    }
+}