feat(WEB): 작업지시/출근부 기능 개선 및 마이그레이션 추가

- 작업지시 우선순위 필드 추가 (priority 마이그레이션)
- 수주-작업지시 품목 연동 source_order_item_id 컬럼 추가
- 수주 테이블에 account_code 필드 추가
- 작업지시 StoreRequest/UpdateRequest 우선순위 검증 추가
- WorkOrder 모델 priority fillable 추가
- 출근부 StoreRequest/UpdateRequest 검증 규칙 개선
- Employee Request 검증 규칙 수정
- SaleService/ItemService 수정
- WorkResultService 결과 처리 개선
- BankTransactionService 수정
- routes/api.php 엔드포인트 업데이트
- error.php 에러 메시지 추가

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

database/migrations/2026_01_15_172302_add_account_code_to_sales_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.
+     */
+    public function up(): void
+    {
+        Schema::table('sales', function (Blueprint $table) {
+            $table->string('account_code', 50)->nullable()->after('status')->comment('계정과목코드');
+            $table->index('account_code', 'idx_account_code');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('sales', function (Blueprint $table) {
+            $table->dropIndex('idx_account_code');
+            $table->dropColumn('account_code');
+        });
+    }
+};

database/migrations/2026_01_16_100000_add_priority_to_work_orders_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
+{
+    /**
+     * 작업지시 테이블에 우선순위 컬럼 추가
+     */
+    public function up(): void
+    {
+        Schema::table('work_orders', function (Blueprint $table) {
+            $table->unsignedTinyInteger('priority')->default(5)->after('status')
+                ->comment('우선순위: 1(긴급)~9(낮음), 기본값 5(일반)');
+            $table->index(['tenant_id', 'priority'], 'idx_work_orders_tenant_priority');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('work_orders', function (Blueprint $table) {
+            $table->dropIndex('idx_work_orders_tenant_priority');
+            $table->dropColumn('priority');
+        });
+    }
+};