feat(server): add GET /attachment/status with derived boxed qty

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

app/api/v1/attachment.py

@@ -3,7 +3,8 @@ from sqlalchemy.orm import Session
 
 from app.core.database import get_db
 from app.models.attachment import AttachmentCategory
-from app.schemas.attachment import CategoryResponse
+from app.schemas.attachment import AttachmentStatusResponse, CategoryResponse
+from app.services.attachment_service import get_attachment_status
 
 router = APIRouter(tags=["attachment"])
 
@@ -20,3 +21,8 @@ def list_categories(db: Session = Depends(get_db)):
     return [
         CategoryResponse(id=r.id, name=r.name, sort_order=r.sort_order) for r in rows
     ]
+
+
+@router.get("/attachment/status", response_model=AttachmentStatusResponse)
+def attachment_status(zongpai_no: str, db: Session = Depends(get_db)):
+    return get_attachment_status(db, zongpai_no)