v0.9.0

What's Changed

• ci: guard hardening — stdio smoke, OS matrix, latency budget, pack guard (F5 Batch 3) by @arturogarrido in #77
• feat: post-tournament readiness — spawn-loop fix, derived KO window, backoff (0.9.0, F5 Batch 2) by @arturogarrido in #78

Full Changelog: v0.8.19...v0.9.0