Hydrate the OpenRouter catalog on cold runtime resolution (#678)

* Hydrate the OpenRouter catalog on cold runtime resolution

An approved dynamic OpenRouter model (e.g. stealth/ox-alpha) only exists
in a process after the catalog has been fetched. #656 pre-warmed the
catalog on the API turn entrypoint, but the harness router's own
resolution path (wiring.ts) had no such warm-up, so a run landing on a
cold worker rejected the selection with "runtime pi/<model> is not
approved".

resolveRuntimeChoiceDurable now accepts an optional catalog hydrator and
invokes it before resolving whenever any candidate model is unknown to
the local registry; wiring passes one that fetches the OpenRouter
catalog when an OpenRouter key is available. A warm registry never
triggers a fetch.

Co-Authored-By: QM <qm@ycombinator.com>

* Remove inline comments

Co-Authored-By: QM <qm@ycombinator.com>

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Co-authored-by: QM <qm@ycombinator.com>