feat(WEB): 절곡품 선생산→재고적재 Phase 1 - 생산입고 기반 구축

- StockTransaction: REASON_PRODUCTION_OUTPUT 상수 및 '생산입고' 라벨 추가
- StockLot: work_order_id FK 컬럼 마이그레이션 + 모델 fillable/casts/relation 추가
- StockService: increaseFromProduction() 메서드 구현 (increaseFromReceiving 기반)
- WorkOrderService: 완료 시 sales_order_id 유무에 따라 출하/재고입고 분기
  - stockInFromProduction(): 품목별 양품 재고 입고 처리
  - shouldStockIn(): items.options 기반 입고 대상 판단

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

app/Models/Tenants/StockTransaction.php

@@ -48,12 +48,15 @@ class StockTransaction extends Model
 
     public const REASON_ORDER_CANCEL = 'order_cancel';
 
+    public const REASON_PRODUCTION_OUTPUT = 'production_output';
+
     public const REASONS = [
         self::REASON_RECEIVING => '입고',
         self::REASON_WORK_ORDER_INPUT => '생산투입',
         self::REASON_SHIPMENT => '출하',
         self::REASON_ORDER_CONFIRM => '수주확정',
         self::REASON_ORDER_CANCEL => '수주취소',
+        self::REASON_PRODUCTION_OUTPUT => '생산입고',
     ];
 
     protected $fillable = [
@@ -111,4 +114,4 @@ public function getReasonLabelAttribute(): string
     {
         return self::REASONS[$this->reason] ?? ($this->reason ?? '-');
     }
-}
+}