fix: set filename in file download response

dashboard/backend/routers/files.py

@@ -94,7 +94,7 @@ def download(path: str):
         target = _safe_path(path)
         if not target.exists():
             raise HTTPException(status_code=404, detail="File not found")
-        return FileResponse(target)
+        return FileResponse(target, filename=target.name)
     except ValueError:
         raise HTTPException(status_code=403, detail="Access denied")