Release 1.24.0

No fake green in readiness (roadmap WS-Q task 7: "skipped counts as yellow; nothing may be marked green by being synthesised from skipped parts"). ready.js had only ok and fail, so a check whose feature was not configured had to claim ok (Network's Discord bot, Media's events outbox and News's source pull did) or fail and turn the service yellow for a setting.

• skip(reason, detail?), exported by openvibe-shared/ready, or a check returning { skipped: reason }: the check reports status skipped with reason (and detail), never ok, and is listed in the new skipped array of the body.
• A skipped optional check leaves a service whose other checks passed ready. A skipped required check is listed in degraded too, and the service is degraded (still HTTP 200: nothing failed).
• A service is ready only when at least one check really passed: one with no checks, or with every check skipped, is degraded. This changes what a service with no checks reports (before: ready).