Implements the five deferred follow-ups from the Audit Log #23 roadmap:
- Real ClusterClient-based site->central audit push (replaces NoOpSiteStreamAuditClient)
- Consolidated the duplicated AuditEvent/SiteCall DTO mappers
- Site Calls UI page + read-side backend + central->site Retry/Discard relay + Health KPI tiles
- Multi-value AuditLogQueryFilter end-to-end (repository, ManagementService, CLI, Central UI)
- Audit results grid column resize/reorder UX
Full solution build clean; full test suite green including Playwright 60/60.
Joseph Doherty