scripts/smoke.ts waits for --version on /healthz and checks that /sw.js never answers a navigation with an error #2340

Part of #2282.

Done looks like:

• [ ] --version <v> polls /healthz until X-Forge-Version equals <v>, up to a limit, before any other check runs. It fails with the last version it saw.
• [ ] /sw.js must be a 200 JavaScript response, and no navigation path in it may answer with Response.error().
• [ ] The stub tests are extended: a version that arrives late passes, one that never arrives fails, and a sw.js that uses Response.error() on navigation fails. Touch only the script, its test and the GATE line.

Parked by the crew: the check failed ("the owner's screen with snapshots > a store with a newest snapshot and a mirror: where, mirror, last, and the shared-volume need as an act row") and the decider saw no point in another try (pull #2362 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Parked by the crew: the check failed ("the owner's screen with snapshots > a store with a newest snapshot and a mirror: where, mirror, last, and the shared-volume need as an act row") and the decider saw no point in another try (pull #2372 closed).

Parked twice since a person last spoke here, so it is the planner's now. Every reason:

1. the check failed ("the owner's screen with snapshots > a store with a newest snapshot and a mirror: where, mirror, last, and the shared-volume need as an act row") and the decider saw no point in another try (pull #2362 closed)
2. the check failed ("the owner's screen with snapshots > a store with a newest snapshot and a mirror: where, mirror, last, and the shared-volume need as an act row") and the decider saw no point in another try (pull #2372 closed)

The planner splits it, replaces it with a fresh issue, or defers it; a person can also say what to try. Nothing starts here until then, and the board lists it.

Replaced by #2388, after #2387. Both tries, and both of #2282's before them, went red on test/resilience.test.ts's snapshot test, which expects the owner's whole screen to say 'all fine'. #2387 makes that test read only its own rows first. #2388 then keeps the smoke test free of globals and env changes, and runs it together with resilience.