feat:sales_tenant_managements 테이블에 handover_at 컬럼 추가

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

database/migrations/2026_02_19_000001_add_handover_at_to_sales_tenant_managements.php

@@ -0,0 +1,22 @@
+<?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::table('sales_tenant_managements', function (Blueprint $table) {
+            $table->datetime('handover_at')->nullable()->after('hq_status');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('sales_tenant_managements', function (Blueprint $table) {
+            $table->dropColumn('handover_at');
+        });
+    }
+};