Land the 3-day-conflicted crew pull sweep from branch scout/5940-a-crew-pull-that-has-stayed-conflicted-f, with its event kind classified for its audience #6559

Replaces #5940. The sweep is written and its own tests pass (pull #6544, closed). Its last check was red on one test: test/event-audience-coverage.test.ts ("every kind the source emits is classified"). The new close event's kind is not listed in src/core/event_audience.ts.

Done:

• [ ] Branch scout/5940-a-crew-pull-that-has-stayed-conflicted-f (head 8a14fb6c) is brought up to date with main and opened as a new pull.
• [ ] Every event kind the sweep emits is classified in src/core/event_audience.ts: for whoever can read the repository, the same as pull.closed. bun test test/event-audience-coverage.test.ts passes.
• [ ] What #5940 asked for still holds: a crew pull conflicted for 72 h with no push and no hold is closed with one line, its branch kept and its issue made ready again; a person's pulls, held pulls and pulls approved after the conflict are never closed; the tick line names today's count; test/stale_pulls.test.ts covers 71 h and 73 h.

Files: src/crew/stale_pulls.ts, src/core/event_audience.ts, test/stale_pulls.test.ts, and the wiring already on the branch.

Before pushing: bun x tsc --noEmit, bun test test/stale_pulls.test.ts test/event-audience-coverage.test.ts.