fix(correlation): Keep-Alive time window + orphan timer + TTL purge (v1.1.14)

Bug #1 - processSourceA: utilise bEventHasValidTTL en mode one_to_many
  au lieu de eventsMatch qui comparait les timestamps originaux. Apres ~10s
  les requetes A devenaient toutes orphelines alors que la session KA etait active.

Bug #4 - checkPendingOrphansForCorrelation: meme correction, cle identique
  = meme connexion en one_to_many, pas besoin de comparer les timestamps.

Bug #3 - cleanNetworkBufferByTTL: expiration B => emission immediate
  des pending orphans associes (ils ne peuvent plus jamais corréler).

Bug #2 - Orchestrateur: goroutine ticker 250ms appelle EmitPendingOrphans()
  pour drainer les orphans independamment du flux d'evenements entrants.
  EmitPendingOrphans() expose la methode comme publique thread-safe.

Tests: 4 nouveaux tests de non-regression (un par bug).

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

internal/app/orchestrator.go

@@ -15,6 +15,10 @@ const (
 	DefaultEventChannelBufferSize = 1000
 	// ShutdownTimeout is the maximum time to wait for graceful shutdown
 	ShutdownTimeout = 30 * time.Second
+	// OrphanTickInterval is how often the orchestrator drains pending orphans.
+	// Set to half the default emit delay (500ms/2) so orphans are emitted promptly
+	// even when no new events arrive.
+	OrphanTickInterval = 250 * time.Millisecond
 )
 
 // OrchestratorConfig holds the orchestrator configuration.
@@ -77,6 +81,27 @@ func (o *Orchestrator) Start() error {
 		}(source, eventChan)
 	}
 
+	// Start a periodic ticker to drain pending orphan A events independently of the
+	// event flow. Without this, orphans are only emitted when a new event arrives,
+	// causing them to accumulate silently when the source goes quiet.
+	o.wg.Add(1)
+	go func() {
+		defer o.wg.Done()
+		ticker := time.NewTicker(OrphanTickInterval)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-o.ctx.Done():
+				return
+			case <-ticker.C:
+				logs := o.correlationSvc.EmitPendingOrphans()
+				for _, log := range logs {
+					o.config.Sink.Write(o.ctx, log) //nolint:errcheck
+				}
+			}
+		}
+	}()
+
 	return nil
 }