fix: enforce Beijing Time (UTC+8) globally by replacing datetime.utcnow

inventory-backend/app/api/v1/stock/adjustment.py

@@ -2,7 +2,7 @@
 from flask import Blueprint, request, jsonify
 from flask_jwt_extended import jwt_required, get_jwt_identity, get_jwt
 from app.utils.decorators import permission_required
-from app.extensions import db
+from app.extensions import db, beijing_time
 from app.models.stock.adjustment import StockAdjustment
 from app.models.base import MaterialBase
 from app.models.inbound.buy import StockBuy
@@ -17,7 +17,7 @@ adjustment_bp = Blueprint('adjustment', __name__, url_prefix='/stock/adjustment'
 
 def get_beijing_time():
     """获取北京时间 (UTC+8)"""
-    return datetime.utcnow() + timedelta(hours=8)
+    return beijing_time()
 
 
 def generate_order_no():