Initialize narratio Go module and CLI scaffold

internal/manifest/status.go

@@ -0,0 +1,14 @@
+package manifest
+
+// StageStatus is the lifecycle state of a pipeline stage.
+type StageStatus string
+
+const (
+	StatusPending     StageStatus = "pending"
+	StatusRunning     StageStatus = "running"
+	StatusSucceeded   StageStatus = "succeeded"
+	StatusFailed      StageStatus = "failed"
+	StatusSkipped     StageStatus = "skipped"
+	StatusStale       StageStatus = "stale"
+	StatusInterrupted StageStatus = "interrupted"
+)