Close only for who may on the change page; a failed crew change keeps its decision behind a review gate; the composer fits 360 px #856

The follow-ups the reviews of #703 and #830 asked for (steward build team).

1. Close on the change page is shown only to the change's author or a writer, the same rule as setIssueState (the issue page already does this since #830). Test: "only a change's author or a writer is shown Close: a signed-in stranger on a public change may comment, never close". It fails on main.
2. A crew change whose check failed keeps its decision in a review-gated app ("Tell them" / "Close"), and the reason it gives is the check, not "waits on an approving review". Only the decision that ships (kind look) waits on the review gate. Mirrors still offer none. Test: "in a review-gated app the crew's change whose check failed still offers its decision…". It fails on main.
3. The composer row fits 360 px for a plain issue. On a phone the two buttons drop their icons and keep their full height. Measured at 390 and 360 px on an app tell, a plain issue and a plain change: one row each. Desktop is unchanged.

src/ is three files: change.ts, content.ts and nothing else of substance. Verified: tsc is clean, and studio, studio-words, web-apps, holds, pulls, issues and the five cross files pass (321).

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