Release v0.9.2 — lean CLI packaging, reproducible benchmark, slimmed README

- Version bumped 0.9.1 -> 0.9.2 (pyproject, package, API, Action pins); sync clean.
- CHANGELOG [0.9.2]: packaging, benchmark expansion, honesty wording, README slim.
- README banner + example label updated to v0.9.2.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014Z2Zcqf7F1EawAx23FLwAp