Aligned the archive stage with the new work directory layout

internal/manifest/manifest.go

@@ -29,8 +29,10 @@ type InputRecord struct {
 type ArtifactRecord struct {
 	Kind      string `json:"kind"`
 	LocalPath string `json:"local_path"`
-	RemoteKey string `json:"remote_key,omitempty"`
-	Checksum  string `json:"checksum,omitempty"`
+	// ProducerRunID identifies the run that produced this durable artifact.
+	ProducerRunID string `json:"producer_run_id,omitempty"`
+	RemoteKey     string `json:"remote_key,omitempty"`
+	Checksum      string `json:"checksum,omitempty"`
 }
 
 // StageRecord tracks lifecycle and provenance for one pipeline stage.