Asks come back when their cause changes even without a new check; every kind of ask has its own plural heading #770

Pillar: P1 Feed. Follow-up from the review of #692. One run, fresh from today's main.

Two small faults in how asks collapse and come back (src/web/studio/asks.ts, src/web/studio/asks_page.ts):

1. A row dismissal is compared with each item's own check time. notDismissed treats a dismissal of the row (ask:<kind>:<repoId>) as holding while the dismissal is newer than each item's since, which is its latest check. A pull that was stale (conflicting) when the row was dismissed, and merges again later without a new check, never comes back. Its cause did change (it can ship now), but the comparison misses it. The fix: give an ask's since the moment it last became an ask. For a look ask that is the later of its latest green check and the moment the stale-ask sweep last saw it merge again. A dismissal holds only while it is newer than that.
2. Plural headings fall through to "green changes". rowLine (asks.ts) and rowHead (asks_page.ts) cover parked and stopped; any other kind gets "N green changes wait for your look". Declined and paused are one per repository today, so it does not show yet, but the fallback is wrong by construction. Give every kind its own plural, or refuse to collapse kinds that are one per repository.

Acceptance.

• [ ] A test where a row is dismissed while one of its pulls conflicts, the conflict is resolved without a new check, and the pull asks again.
• [ ] Every DecisionKind has a plural heading, checked by a test that walks the kinds.
• [ ] Reachable: /asks and GET /api/v1/asks show the returned ask. The full check is green.

Must not touch: the release workflow, the chart, other repositories.