The sentinel files a degraded incident once: closed as done, the same incident is commented on, not filed again #2553

Why: one drill incident (first open 2026-10-18T09:11:45Z, the same sentence throughout) has been filed five times today: #2544, the issues behind cf5d784e and 8847dd4f, #2545 and #2552. hunt in src/crew/sentinel.ts files a new issue whenever a finding returns after its issue closed. Each time, the fix was on main but not yet live, so the incident never ended and a builder or the planner was handed a finished issue.

Done looks like:

• [ ] A degraded finding (cause from vitals) remembers the incident it was filed for, by cause and first-open time. If its issue is closed as done while the incident is the same, hunt adds one comment to that closed issue: the new minutes, plus 'still degraded after the fix; the fix may not be live yet'. It does not open a new issue.
• [ ] A new incident (a different first-open time) for the same cause files a new issue, as today. Settings findings and settingKept are unchanged.
• [ ] A closed issue gets at most one such comment per day.
• [ ] Tests in the sentinel's test file: an incident closed as done that continues is commented once, not refiled; a new incident of the same cause is refiled; a finding closed as dropped and returning is refiled as today.