Add cp transfer progress reporting

[acmore]

Summary

• add in-place progress reporting for single-pod and multi-pod
• thread byte/file progress hooks through kube copy helpers
• document tty progress behavior in the command reference

Testing

• env GOCACHE=/tmp/go-build go test ./internal/cli ./internal/kube
• .venv/bin/pre-commit run --all-files --hook-stage manual okdev-gofmt