External Watchdog last-evaluation evidence

The Worker stores a secret-free last_evaluation record after each completed evaluation and exposes it from /status, alongside the current boolean incident_open state. The record covers the evaluation timestamp, action, failure count, incident state and mail outcome.

Verification command:

cd ops/cloudflare/server-beat-watchdog && node --test

Result: 24 tests passed, 0 failed, 0 skipped on 2026-10-02. The targeted tests cover healthy evaluation, the third failed probe with a sent alert, and a failed SES send that leaves the alert queued.