Add OpenRouter harness support

[kenrogers]

Summary

• Add openrouter as a first-class harness selector that runs Codex through OpenRouter.
• Wire OpenRouter credential injection through the firewall/proxy and configure sandbox env/provider selection.
• Normalize OpenRouter events through the Codex event path across Python and TypeScript clients.
• Document OpenRouter setup in quickstart, production, 1Password, index, and architecture docs.

Verification

• uv run ruff check ... over touched Python files
• bash -n services/sandbox/entrypoint.sh
• uv run pytest tests/test_codex_app_wrapper.py -q
• pnpm --filter @centaur/harness-events typecheck
• pnpm --filter @centaur/api-client test -- harness-events.test.ts
• just build-one api and just build-one agent
• Local Helm deploy, then API-pod E2E with harness=openrouter: completed with result_text: "PONG"

Notes

• The broader DB-backed file run currently reports 261 passed, 9 failed; the failures are existing/stale expectations and timing/order assertions outside the OpenRouter path.
• Local Colima testing needed a temporary NetworkPolicy allowing the API pod to reach Colima's Kubernetes apiserver endpoint; no chart/network-policy change is included in this PR.

[arjunblj]

Great contribution! We love OpenRouter. QQ: This should also accept a --model flag, right? (it's unclear to me what model would be piped through Codex in this setup and that seems like a nice thing to be able to specify)

[kenrogers]

Great contribution! We love OpenRouter. QQ: This should also accept a --model flag, right? (it's unclear to me what model would be piped through Codex in this setup and that seems like a nice thing to be able to specify)

Yes good catch! Made an update to accept the --model flag. Also added recovery/reuse handling so a restarted runtime keeps the selected model, plus API/SDK support for structured model selection on spawn.

Let me know if you think any other changes are needed otherwise I will mark as ready for review 🙌🏻

[gakonst]

Superseded #604! Sorry for the delay. Plz give it a try!