refactor: restrict companies to only one contact

backend/database/migrations/2025_10_20_192651_create_companies_table.php

@@ -16,6 +16,7 @@ return new class extends Migration
             $table->string("name")->nullable(false)->unique();
             $table->string("address")->nullable(false);
             $table->unsignedInteger("ico")->nullable(false)->unique();
+            $table->foreignId("contact")->nullable(false)->constrained("users")->onDelete("cascade");
             $table->boolean("hiring")->nullable(false)->default(false);
             $table->timestamps();
         });

backend/database/migrations/2025_10_20_192915_create_employers_table.php

@@ -1,29 +0,0 @@
-<?php
-
-use Illuminate\Database\Migrations\Migration;
-use Illuminate\Database\Schema\Blueprint;
-use Illuminate\Support\Facades\Schema;
-
-return new class extends Migration
-{
-    /**
-     * Run the migrations.
-     */
-    public function up(): void
-    {
-        Schema::create('employers', function (Blueprint $table) {
-            $table->id();
-            $table->foreignId("user_id")->nullable(false)->constrained("users")->onDelete("cascade");
-            $table->foreignId("company_id")->nullable(false)->constrained("companies")->onDelete("cascade");
-            $table->timestamps();
-        });
-    }
-
-    /**
-     * Reverse the migrations.
-     */
-    public function down(): void
-    {
-        Schema::dropIfExists('employers');
-    }
-};