Refactor: refactor dataflow_service.go and guard nats message re-delivery (#16826)

### Summary

1. refactor dataflow_service.go 
2. guard nats message re-delivery
3. support document parse cancelling & re-run

internal/engine/elasticsearch/client.go

@@ -105,6 +105,11 @@ func (e *elasticsearchEngine) GetType() string {
 	return "elasticsearch"
 }
 
+// SupportsPageRank returns true because Elasticsearch supports pagerank.
+func (e *elasticsearchEngine) SupportsPageRank() bool {
+	return true
+}
+
 // Ping health check
 func (e *elasticsearchEngine) Ping(ctx context.Context) error {
 	req := esapi.InfoRequest{}

internal/engine/engine.go

@@ -76,6 +76,9 @@ type DocEngine interface {
 	// GetType returns the engine type
 	GetType() string
 
+	// SupportsPageRank reports whether the engine supports dataset-level pagerank.
+	SupportsPageRank() bool
+
 	// FilterDocIdsByMetaPushdown runs a metadata filter directly against
 	// the doc metadata index, returning matching doc IDs or nil if push-down
 	// is not supported (caller should fall back to in-memory filtering).

internal/engine/infinity/client.go

@@ -191,6 +191,11 @@ func (e *infinityEngine) GetType() string {
 	return "infinity"
 }
 
+// SupportsPageRank returns false because Infinity does not support pagerank.
+func (e *infinityEngine) SupportsPageRank() bool {
+	return false
+}
+
 // Ping checks if Infinity is accessible
 func (e *infinityEngine) Ping(ctx context.Context) error {
 	if e.client == nil || e.client.conn == nil {

internal/engine/nats/nats.go

@@ -253,3 +253,7 @@ func (m *NatsMessageHandle) Ack() error {
 func (m *NatsMessageHandle) Nack() error {
 	return m.message.Nak()
 }
+
+func (m *NatsMessageHandle) InProgress() error {
+	return m.message.InProgress()
+}