Coordinator: heartbeat + lifecycle log lines, request timeouts and log contract

[jjavieralv]

Monitoring for this service is regex-over-logs, so this adds the lines it needs and locks their shape. Everything is confined to packages/guardian-coordinator; no existing log lines were changed.

• Heartbeat: every poll cycle logs {"level":"info","event":"guardian.heartbeat","ok":…,"fetched":…,"signed":…,"skipped":…,"failed":…,"durationMs":…} — also on failed polls (ok:false), so absence always means dead/wedged.
• Lifecycle lines: guardian.startup (build + chains) on boot, guardian.fatal (err + stack) before exit 1, replacing the bare error.message print.
• Request timeouts: REQUEST_TIMEOUT_MS (default 10s) via AbortSignal.timeout on all grunt-api calls — a hung fetch no longer freezes the loop silently.
• Log contract: log-contract.json lists every guaranteed line; tests/log-contract.test.ts checks both directions (every pattern emitted, every emission matched), so changing any monitored line fails CI. These will be used on monitorization patterns to be able to grab the proper logs.
• API (additive, non-breaking): runGuardianCoordinatorOnce now returns the
  cycle's counters (PollCycleStats) instead of void so the heartbeat can report
  them — existing callers are unaffected. New exports: runGuardianCoordinatorCycle
  (one poll + heartbeat, used by the loop and by tests) and startupLine/fatalLine
  (exported only so the contract tests can pin their exact output). New optional
  requestTimeoutMs config field (REQUEST_TIMEOUT_MS). The logger interface is
  untouched.

[changeset-bot]

🦋 Changeset detected

Latest commit: 0861cfb

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@3flabs/guardian-coordinator	Patch

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[LukeHackett12]

once changeset is present happy to merge!