The sentinel files no crew issue for a drill cause: running a drill is a person's, not a builder's #5367

For: no red noise, and no crew run spent on work only a person can do. #5344 (drill:never) was parked twice because a builder cannot run bun scripts/drills/run.ts against production.

Done:

• [ ] ownCause in src/crew/sentinel.ts returns false for a cause starting drill:, as it already does for another repository's red main (#3992). The degraded detector then files nothing for it, while the vitals card (src/kernel/vitals.ts, domainDrillNeeds) still shows it.
• [ ] The doc comment at the top of sentinel.ts names drills among what is left to a person, on purpose.
• [ ] test/sentinel.test.ts: a drill:never span and a drill:compute span degraded past the day budget open no issue; a shared: span of the forge's own repository still does. Each fails without the change.

Files: src/crew/sentinel.ts, test/sentinel.test.ts. Risk: keep shared: and red: behaviour exactly as it is.