perf: 消除 outbound/borrow BOM 匹配的 while(true) 全量加载

## 后端
- outbound.py: 新增 POST /api/v1/outbound/bom-match-stock 端点
  接收 child_ids[]，服务端按 base_id IN 查询三表有库存记录并返回

## 前端
- outbound.ts: 新增 bomMatchStock(childIds) API 函数
- Selection.vue: loadAllStockForBom (while(true) 全量) → loadStockForBom (单次 API)
- borrow/apply/index.vue: 同上

## 效果
- BOM 匹配从 ~90 次 HTTP 请求降为 1 次
- 浏览器内存从 ~18000 条降为 ~8-50 条

inventory-backend/app/api/v1/outbound.py

@@ -199,6 +199,93 @@ def get_outbound_list():
         return jsonify({'code': 500, 'msg': str(e)}), 500
 
 
+# ==============================================================================
+# BOM 匹配库存接口 (POST /api/v1/outbound/bom-match-stock)
+# 替代前端 while(true) 全量加载：服务端按 child_ids 精确查询匹配库存
+# ==============================================================================
+@outbound_bp.route('/bom-match-stock', methods=['POST'])
+@jwt_required()
+def bom_match_stock():
+    """
+    根据 BOM 子件 base_id 列表，查询三张库存表中有库存的匹配记录。
+
+    Body: { "child_ids": [1, 2, 3, ...] }
+    Returns: { "code": 200, "data": { "items": [...] } }
+    """
+    try:
+        data = request.get_json() or {}
+        child_ids = data.get('child_ids', [])
+        if not child_ids:
+            return jsonify({'code': 400, 'msg': 'child_ids 不能为空'}), 400
+
+        # 去重
+        child_ids = list(set(int(x) for x in child_ids))
+
+        from app.models.inbound.buy import StockBuy
+        from app.models.inbound.semi import StockSemi
+        from app.models.inbound.product import StockProduct
+        from sqlalchemy.orm import joinedload
+
+        all_items = []
+
+        # 采购件
+        buy_items = StockBuy.query.filter(
+            StockBuy.base_id.in_(child_ids),
+            StockBuy.stock_quantity > 0
+        ).options(joinedload(StockBuy.base)).all()
+        for s in buy_items:
+            d = s.to_dict()
+            d['type'] = 'material'
+            d['stock_type'] = 'material'
+            d['typeLabel'] = '采购件'
+            d['uniqueKey'] = f"material_{s.id}"
+            d['name'] = d.get('material_name', '')
+            d['standard'] = d.get('spec_model', '')
+            all_items.append(d)
+
+        # 半成品
+        try:
+            semi_items = StockSemi.query.filter(
+                StockSemi.base_id.in_(child_ids),
+                StockSemi.stock_quantity > 0
+            ).options(joinedload(StockSemi.base)).all()
+            for s in semi_items:
+                d = s.to_dict()
+                d['type'] = 'semi'
+                d['stock_type'] = 'semi'
+                d['typeLabel'] = '半成品'
+                d['uniqueKey'] = f"semi_{s.id}"
+                d['name'] = d.get('material_name', '')
+                d['standard'] = d.get('spec_model', '')
+                all_items.append(d)
+        except Exception:
+            pass
+
+        # 成品
+        try:
+            prod_items = StockProduct.query.filter(
+                StockProduct.base_id.in_(child_ids),
+                StockProduct.stock_quantity > 0
+            ).options(joinedload(StockProduct.base)).all()
+            for s in prod_items:
+                d = s.to_dict()
+                d['type'] = 'product'
+                d['stock_type'] = 'product'
+                d['typeLabel'] = '成品'
+                d['uniqueKey'] = f"product_{s.id}"
+                d['name'] = d.get('material_name', '')
+                d['standard'] = d.get('spec_model', '')
+                all_items.append(d)
+        except Exception:
+            pass
+
+        return jsonify({'code': 200, 'msg': 'success', 'data': {'items': all_items}})
+
+    except Exception as e:
+        traceback.print_exc()
+        return jsonify({'code': 500, 'msg': str(e)}), 500
+
+
 # ==============================================================================
 # 出库审批相关接口
 # ==============================================================================