blockmachine

Reviewed overlay for SN19 using the official BlockMachine website, whitepaper, and source repository. 5 community-submitted surfaces had no probe config at all -- the registry-wide gap tracked in #5932 -- fixed. The leaderboard endpoint is consistently slow (~17s across repeated live tests) though genuinely working, not down; timeout extended to 25s so it isn't misreported unhealthy. Diffed the tracked OpenAPI schema (27 paths) against tracked surfaces: found and added the public CLI install script (/install.sh); the remaining untracked paths are either HTTPBearer-auth-gated, X-API-Key-gated, or need a specific epoch_id with no stable canonical value.