chore(lint): clear the six errors that kept CI red since 1.0.0

- install.ts: replace the `navigator as Navigator & { standalone?: unknown }`
  assertion with an `in` guard, so the check is real and no SAFETY claim is
  needed.
- sys.ts: `netFailure` takes the message it stores, not `unknown`. The two
  catch clauses narrow the throw to its text, keeping the parse at the
  boundary that caught it.
- update.ts: `toSorted()` / `toReversed()` on the freshly filtered arrays.
- update.test.ts: the manifest fixture and its override are `JsonObject`,
  the document `parseReleaseManifest` reads, not `Record<string, unknown>`.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>