A hold placed because a pull was red releases itself when that pull's check is green on the same head #6348

Part of #5930 (the steward's trap 2): 7 "red alone, held" holds outlived their reason.

Done:

• [ ] A hold placed for red (by the steward or the landing pass) is released by the forge's tick when the pull's check on its current head is green. A note on the pull says so in one line.
• [ ] Any automatic hold still standing after 24 h is released with a note. A hold a person placed by hand is never touched.
• [ ] Tests: green on the same head releases; green on an older head does not; a person's hold stays.

Files: src/core/holds.ts (a release with a reason), the tick that reads checks, a test.

Before pushing: bun x tsc --noEmit and the tests you add or touch; bun scripts/design-lint.ts if src/web/ changes. Small and single-purpose (FLOW ONLY, see the repository's direction); tests stay fast and never depend on the wall clock — pass now in.

Replaced by #6847. Parked twice on small asks: the docblock wrap, and the fact that nothing passes forRed yet. #6831 now owns who places red holds, and it waits for #6847.