Reconcile builds stuck after missed completion events

## Intent
Add a scheduled action that reconciles builds whose persisted state or GitHub check status is stale because an Azure DevOps completion event was missed.

## Requirements
- Periodically find a bounded set of builds that remain in a non-terminal state beyond an appropriate age threshold.
- Query Azure DevOps for authoritative completion state and repair the corresponding Build Insights state and GitHub check when needed.
- Make reconciliation idempotent and safe to retry.
- Configure a conservative frequency, lookback window, batch size, and query limits.
- Avoid unnecessary Azure DevOps and GitHub requests by filtering locally where possible and skipping already-terminal builds.
- Emit enough telemetry to measure scanned, reconciled, skipped, and failed builds.

## Goal
Ensure missed Azure DevOps completion events cannot leave GitHub checks in progress indefinitely, without introducing an expensive polling workload against Azure DevOps or GitHub.