feat: [approval] approvals 테이블에 rejection_history JSON 컬럼 추가

database/migrations/2026_03_05_163000_add_rejection_history_to_approvals_table.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('approvals', function (Blueprint $table) {
+            $table->json('rejection_history')->nullable()->after('resubmit_count');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('approvals', function (Blueprint $table) {
+            $table->dropColumn('rejection_history');
+        });
+    }
+};