🔥 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/migrations/2026_05_02_155301_create_countries_table.php

@@ -0,0 +1,24 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('countries', function (Blueprint $table) {
+            $table->id();
+            $table->string('name');
+            $table->string('code', 8)->unique();
+            $table->json('language_codes')->nullable();
+            $table->timestamps();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('countries');
+    }
+};