fix:quotes 목록 조회 시 MySQL Out of sort memory 에러 해결

- quotes(tenant_id, registration_date, id) 복합 인덱스 추가
- ORDER BY registration_date DESC, id DESC 정렬 시 filesort 제거

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

database/migrations/2026_02_13_092247_add_composite_index_to_quotes_table.php

@@ -0,0 +1,28 @@
+<?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::table('quotes', function (Blueprint $table) {
+            $table->index(['tenant_id', 'registration_date', 'id'], 'idx_quotes_tenant_registration_id');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('quotes', function (Blueprint $table) {
+            $table->dropIndex('idx_quotes_tenant_registration_id');
+        });
+    }
+};