The changelog's top line reads "Live: 8a16183" on a build that is not a release, not "Live: dev · 8a16183" #7939

Intent: dense, never nerdy — the first line of /changelog says what is running in words a person reads at once.

Seen on production today (https://lab--forge-trevato-apps.open-platform.sh/changelog): "Live: dev · 8a16183." A forge run from a commit that is not a tagged release gets the version dev (src/release/launch.ts), and shippedRegion prints it before the commit.

Done:

• [ ] When the version is dev and a commit is known, the line reads Live: <short sha> linked to that commit's page, as the door links its serving commit; with neither a release nor a commit it reads Live: a development build.
• [ ] A release keeps Live: <version> · <short sha> exactly as now.
• [ ] The terminal's Changelog screen says the same words, if it prints the version.
• [ ] Tests in test/changelog.test.ts fail without the change: dev plus a commit renders the short sha and no dev; a release version is unchanged.
• [ ] By eye on a preview: /changelog's first line has no dev.

Files: src/web/pages/changelog.ts, test/changelog.test.ts (and src/tui/screens/changelog.ts with test/tui-changelog.test.ts only if it prints dev).