Make room for probes of other CUDA classes. common.py and gpu_span.py
stay in perf/ and become shared; the cluster-finder driver, traced
process, README and results move to perf/cf/.
- common.py: assert_build_fresh() takes the header list, capture_env()
takes extra fields, results_dir() takes the probe folder.
- cf/cf_common.py: pedestal frames, n_sigma, rebuild-guard headers,
DEVICE_PED_TYPE and the <date>_<f32|f64> results naming.
- gpu_span.py: optional kernel-name filter; tolerates an engine with no
ops. Output without a filter is unchanged.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
