Replace plain String.equals() with MessageDigest.isEqual() for
constant-time HMAC signature comparison. Switch from manual StringBuilder
JSON to Jackson ObjectMapper. Add typed Java records for game state,
moves, and config.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Add forkable starter kit templates for Python, Go, JavaScript, Rust,
Java, and C# — each with HTTP server scaffold, HMAC auth, game types,
random strategy, Dockerfile, and GHCR workflow. Update /compete/docs
page with starter kit links and registration instructions.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
