Wave 2 prep: LedgerEvent.ref, demo bridge protocol, artifact stubs, sendText in ChatActionsContext

components/artifacts/demo-card.tsx

@@ -0,0 +1,10 @@
+import type { ArtifactPartProps } from "@/src/core/contracts";
+
+/**
+ * Demo artifact card (W6): sandboxed iframe rendering DemoResult.html with
+ * the auto-injected resize/error bridge (contracts.ts "Demo iframe bridge").
+ * While input-available: job activity card (poll /api/jobs).
+ */
+export function DemoCard(_props: ArtifactPartProps) {
+	return null;
+}