feat:분개 테이블에 공급가액/부가세 컬럼 추가

- split_supply_amount (decimal 18,2, nullable) 컬럼 추가
- split_tax (decimal 18,2, nullable) 컬럼 추가

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

database/migrations/2026_02_05_400000_add_supply_tax_to_barobill_card_transaction_splits_table.php

@@ -0,0 +1,30 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     * 분개 테이블에 공급가액/부가세 컬럼 추가
+     */
+    public function up(): void
+    {
+        Schema::table('barobill_card_transaction_splits', function (Blueprint $table) {
+            $table->decimal('split_supply_amount', 18, 2)->nullable()->after('split_amount')->comment('분개 공급가액');
+            $table->decimal('split_tax', 18, 2)->nullable()->after('split_supply_amount')->comment('분개 부가세');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('barobill_card_transaction_splits', function (Blueprint $table) {
+            $table->dropColumn(['split_supply_amount', 'split_tax']);
+        });
+    }
+};