Add prompt input materials and session IDs

internal/core/artifacts/artifacts.go

@@ -75,6 +75,7 @@ type RunManifest struct {
 	ArtifactLanes    []ArtifactLaneManifest    `json:"artifact_lanes,omitempty"`
 	References       []ReferenceProvenance     `json:"references,omitempty"`
 	LLMProfiles      []LLMProfileManifest      `json:"llm_profiles,omitempty"`
+	Metadata         map[string]any            `json:"metadata,omitempty"`
 	SchemaVersion    string                    `json:"schema_version,omitempty"`
 	ValidationStatus string                    `json:"validation_status,omitempty"`
 	StartedAt        *time.Time                `json:"started_at,omitempty"`