feat: observability, IP filtering, stdout/clickhouse fixes (v1.1.11)

- feat(observability): metrics server with /metrics and /health endpoints
- feat(observability): correlation metrics (events, success/failed, reasons, buffers)
- feat(correlation): IP exclusion filter (exact IPs and CIDR ranges)
- feat(correlation): pending orphan delay for late-arriving B events
- fix(stdout): sink is now a no-op for data; JSON must never appear on stdout
- fix(clickhouse): all flush errors were silently discarded, now properly logged
- fix(clickhouse): buffer overflow with DropOnOverflow now logged at WARN
- fix(clickhouse): retry attempts logged at WARN with attempt/delay/error context
- feat(clickhouse): connection success logged at INFO, batch sends at DEBUG
- feat(clickhouse): SetLogger() for external logger injection
- test(stdout): assert stdout remains empty for correlated and orphan logs
- chore(rpm): bump version to 1.1.11, update changelog
- docs: README and architecture.yml updated

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

internal/adapters/inbound/unixsocket/source.go

@@ -164,9 +164,9 @@ func (s *UnixSocketSource) readDatagrams(ctx context.Context, eventChan chan<- *
 			continue
 		}
 
-		// Debug: log raw events
-		s.logger.Debugf("event received: source=%s src_ip=%s src_port=%d",
-			event.Source, event.SrcIP, event.SrcPort)
+		// Debug: log raw events with all key details
+		s.logger.Debugf("event received: source=%s src_ip=%s src_port=%d timestamp=%v raw_timestamp=%v",
+			event.Source, event.SrcIP, event.SrcPort, event.Timestamp, event.Raw["timestamp"])
 
 		select {
 		case eventChan <- event: