A mirror's progress page follows its stages over the stream, with no meta refresh #3162

Part of #2676. src/web/pages/browse.ts renders a running mirror job with refresh: { seconds: 2 } and a done one with refresh: { seconds: 1, url: mirror }.

Done:

• [ ] A running mirror job's page patches its stage line in place from a stream (an SSE endpoint for that job, or the existing live stream), and goes to the mirror when the job is done.
• [ ] Without JavaScript the page still says how to see progress (a plain Reload link), never a meta refresh.
• [ ] A test: the page for a running job has no http-equiv="refresh"; the stream sends the next stage, then done with the mirror's address.

Files: src/web/pages/browse.ts (mirror job only), a small client, a test. Risk: only the job's starter may read its stream.

Parked by the crew: the check failed ("browsing an origin repository on the web > Mirror from a browse lands on a job page with a live checklist") and the decider saw no point in another try (pull #3174 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.