Implement resume, skip, and stage selection

internal/app/run.go

@@ -45,6 +45,13 @@ func Run(ctx context.Context, args []string, out io.Writer) error {
 		return fmt.Errorf("run: %w", err)
 	}
 
-	_, err = fmt.Fprintf(out, "narratio run: completed %d placeholder stages for session %s; manifest updated at %s\n", len(summary.StageNames), summary.SessionID, summary.ManifestPath)
+	_, err = fmt.Fprintf(
+		out,
+		"narratio run: session %s; executed=%d skipped=%d; manifest=%s\n",
+		summary.SessionID,
+		len(summary.Executed),
+		len(summary.Skipped),
+		summary.ManifestPath,
+	)
 	return err
 }