Run the complete live stack reliably on PRs and canaries

[dimavrem22]

Summary

• replace independent live workflows with one queued channels → voice → external-events orchestrator and required aggregate result
• run the complete stack for ready same-repo PRs and after each successful twice-daily canary
• page scheduled failures from either canary host lane or any live-stack component
• fold lint, full unit/contract tests, and build into the named required lane before removing duplicate CI
• upgrade GitHub actions to Node 24 releases
• correlate email checks with substantive new deliveries and make external events assert HMAC plus real-model turn completion while voice retains real call coverage

Validation

• npm run lint
• npm run typecheck
• npm test — 51 files and 641 tests passed
• npm run build
• actionlint with the older local schemas concurrency.queue warning ignored
• git diff --check

This PR is intentionally unmerged and ready for review.