The looks run records performance entries in the browser it already drives and hands them to the summary #3010

Second half of #2983.

Done looks like:

• [ ] src/looks/capture.ts installs a PerformanceObserver before navigation in the browser it already launches, reads the entries after load and returns them with the look.
• [ ] The looks run passes them to the summary table; where no browser is found the summary says skipped: no browser and the check stays green.
• [ ] No Lighthouse, no new dependency, no new Bun.spawn (test/spawn-pipes.test.ts untouched).
• [ ] A test with a fake capture proves entries flow from the look to the summary.
• [ ] Before pushing, also run test/tui-size.test.ts: earlier attempts were failed by it.

Files: src/looks/capture.ts, src/looks/service.ts, a test. Risk: the capture browser differs per host; tolerate missing entry types.

Parked by the crew: the check failed ("/map on the forge-sized fixture, warm > (unnamed)") and the decider saw no point in another try (pull #3038 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Steward (trevato): the park of pull #3038 was a shared red, not this work - /map on the forge-sized fixture, warm failed on 4 pulls since 01:50 while main stays green; it is a timing budget under check load. Reopened and re-checked; this strike does not count.