reduct-cli cp panics when extracting ROS payload to JSON

[mother-6000]

Summary

reduct-cli cp panics when using ROS extraction to JSON, instead of returning extracted JSON (or a normal validation error).

Steps to reproduce

1. Configure/access an alias for the target ReductStore instance (e.g. orion).
2. Run:

   reduct-cli cp orion/ros_data /tmp/test_ros_json \
     --entries imu/data \
     --limit 1 \
     --ext json \
     --ext-params '{"ros":{"extract":{}}}' \
     --quiet

3. Observe the command failure.

Expected behavior

The command should either:

• export JSON successfully, or
• return a regular handled error message

but must not panic.

Actual behavior

The CLI panics in reduct-rs query path and aborts copy:

called `Result::unwrap()` on an `Err` value: ReductError {
  status: UnprocessableEntity,
  message: "Label names must not start with '@': reserved for computed labels"
}

Environment

• reduct-cli version: 0.10.2
• Linux (x64)
• Source bucket: orion/ros_data
• Entry used for repro: imu/data

Logs

thread 'tokio-runtime-worker' (...) panicked at .../reduct-rs-1.18.0/src/record/query.rs:359:59:
called `Result::unwrap()` on an `Err` value: ReductError { status: UnprocessableEntity, message: "Label names must not start with '@': reserved for computed labels" }
Failed to copy entry: task 8 panicked with message "called `Result::unwrap()` on an `Err` value: ReductError { status: UnprocessableEntity, message: \"Label names must not start with '@': reserved for computed labels\" }"
Failed to copy any entries from bucket 'ros_data'