Deployment Manager: add deployment concurrency rules (block same-instance, allow
parallel different-instance), per-site artifact deployment status, current-only
status persistence.
Central UI: specify Blazor Server framework, real-time push updates via SignalR
for debug view, health dashboard, and deployment status.
Site Event Logging: daily retention purge, paginated queries with 500-event default,
keyword search on message/source fields.
Store-and-Forward: clarify async best-effort replication to standby with acceptable
trade-offs on failover.
