fix: unify error response format with error_code, message and domain fields

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

app/api/v1/location.py

@@ -2,13 +2,27 @@ from fastapi import APIRouter, Depends
 from sqlalchemy.orm import Session
 
 from app.core.database import get_db
+from app.schemas.common import ErrorResponse
 from app.schemas.location import LocationRequest, LocationResponse
 from app.services.location_service import register_location
 
 router = APIRouter()
 
 
-@router.post("/location", response_model=LocationResponse)
+@router.post(
+    "/location",
+    response_model=LocationResponse,
+    responses={
+        400: {
+            "description": "总排号或货位号格式不合法",
+            "model": ErrorResponse,
+        },
+        409: {
+            "description": "该总排号已存在货位记录",
+            "model": ErrorResponse,
+        },
+    },
+)
 def create_location(req: LocationRequest, db: Session = Depends(get_db)):
     record = register_location(db, req)
     return LocationResponse(