feat(correlation): add configurable delay before emitting orphan A events

New feature: Apache events can now wait for B events before being emitted as orphans.

Changes:
- Add ApacheEmitDelayMs config (default: 500ms)
- Add pendingOrphans structure for delayed emission
- processSourceA(): add A to pending orphans instead of immediate emission
- processSourceB(): check pending orphans before buffer A
- emitPendingOrphans(): emit orphans after delay expires
- Flush(): emit all pending orphans immediately (shutdown)

Configuration:
correlation:
  orphan_policy:
    apache_always_emit: true
    apache_emit_delay_ms: 500  # Wait 500ms before emitting as orphan

Backward compatibility:
- apache_emit_delay_ms: 0 → immediate emission (legacy mode)
- apache_emit_delay_ms < 0 → default 500ms

Tests added (5 new tests):
- TestCorrelationService_ApacheEmitDelay_BArrivesDuringDelay
- TestCorrelationService_ApacheEmitDelay_NoBArrives
- TestCorrelationService_ApacheEmitDelay_ZeroDelay
- TestCorrelationService_ApacheEmitDelay_MultipleA_SameKey
- TestCorrelationService_ApacheEmitDelay_Flush

All 30 tests pass. Coverage: 75.1%

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

cmd/logcorrelator/main.go

@@ -108,6 +108,7 @@ func main() {
 	correlationSvc := domain.NewCorrelationService(domain.CorrelationConfig{
 		TimeWindow:         cfg.Correlation.GetTimeWindow(),
 		ApacheAlwaysEmit:   cfg.Correlation.GetApacheAlwaysEmit(),
+		ApacheEmitDelayMs:  cfg.Correlation.GetApacheEmitDelayMs(),
 		NetworkEmit:        false,
 		MaxHTTPBufferSize:  cfg.Correlation.GetMaxHTTPBufferSize(),
 		MaxNetworkBufferSize: cfg.Correlation.GetMaxNetworkBufferSize(),
@@ -118,9 +119,10 @@ func main() {
 	// Set logger for correlation service
 	correlationSvc.SetLogger(logger.WithFields(map[string]any{"component": "correlation"}))
 
-	logger.Info(fmt.Sprintf("Correlation service initialized: time_window=%s, emit_orphans=%v",
+	logger.Info(fmt.Sprintf("Correlation service initialized: time_window=%s, emit_orphans=%v, emit_delay_ms=%d",
 		cfg.Correlation.GetTimeWindow().String(),
-		cfg.Correlation.EmitOrphans))
+		cfg.Correlation.GetApacheAlwaysEmit(),
+		cfg.Correlation.GetApacheEmitDelayMs()))
 
 	// Create orchestrator
 	orchestrator := app.NewOrchestrator(app.OrchestratorConfig{