Let the tracing label go away with the feature
main fails make rs-check (Rust Tests red at 5680b25) since #165 met the --no-default-features clippy pass that landed with the CI hardening: trace::label, is_raw and the OperationInfo import exist only to name spans and events, and without the tracing feature the event macros expand to nothing, so nothing asks for the label and clippy's -D dead-code refuses the build. All three, and the import in client.rs, now go away with the feature.
Three #[cfg] lines, no behaviour change. Every Rust PR rebased onto main fails the gate until this lands, so it goes ahead of #168 and #169.
Gate: make rs-check (default, --no-default-features, --all-features), on main + this commit, green.
Summary by cubic
Gates the tracing label helpers behind the tracing feature so --no-default-features builds pass clippy's dead-code check. No behavior change.