🔥 Add initial database migrations, seeders, and factories

🎨 Refactor `Lecturer` model to include new fields and factory usage
🔧 Update `DatabaseSeeder` to handle default seeds
🛠️ Enhance `einundzwanzig` database configuration for SQLite compatibility

database/factories/VenueFactory.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace Database\Factories;
+
+use App\Models\City;
+use App\Models\Venue;
+use Illuminate\Database\Eloquent\Factories\Factory;
+
+/**
+ * @extends Factory<Venue>
+ */
+class VenueFactory extends Factory
+{
+    /**
+     * @return array<string, mixed>
+     */
+    public function definition(): array
+    {
+        return [
+            'city_id' => City::factory(),
+            'name' => fake()->randomElement(['Bitcoin Bar', 'Plebsfreundlicher Coworking', 'Hodler Hangout', 'Lightning Lounge']).' '.fake()->lastName(),
+            'description' => fake()->paragraph(),
+            'address' => fake()->streetAddress(),
+            'website' => fake()->url(),
+        ];
+    }
+
+    public function bitcoinBarVienna(): static
+    {
+        return $this->state(fn () => [
+            'name' => 'Bitcoin Bar Wien',
+            'description' => 'Die erste Bitcoin-only Bar im 7. Bezirk.',
+            'address' => 'Neubaugasse 21, 1070 Wien',
+            'website' => 'https://bitcoin-bar.at',
+        ]);
+    }
+}