v1.31.0

What's Changed

• chore(release): fail-closed gates + backfilled changelog by @druide67 in #79
• feat(bench): read prefix-cache hits (usage cached_tokens) in code_eval.chat by @druide67 in #80
• feat(web): bench page craft pass — rich model picker, error state, eta (design handoff) by @druide67 in #81
• feat(web): "This machine vs community" compare panel on the Leaderboard (ADR 0002) by @druide67 in #82

Full Changelog: v1.30.0...v1.31.0