v0.2.1

What's new

• Reusable GitHub Action — uses: MerlijnW70/cu-profiler@v1 installs the CLI and runs cu-profiler ci (or any subcommand) in one line. No peer in the field ships one.
• Actionable bench onboarding — when the Linux cu-profiler-bench executor is missing, the error now prints the exact install command instead of a vague hint. New docs/bench.md walkthrough.
• Hardened test suite — zero-survivor mutation testing across cu-profiler-core/-report plus a dense float-clause property/law sweep.

All four crates (cu-profiler-core, -instrumentation, -report, -cli) published to crates.io at 0.2.1. No public API changes.