feat(FN-3505): add node onboarding mapping flow with asset-gated bundling

- Add onboarding project-mapping API contracts and dashboard UI wiring in AddNodeModal/NodesView
- Persist node-to-project mappings with rollback-safe failure handling and expanded hook/API test coverage
- Document node onboarding mapping behavior in architecture and multi-project docs
- Add tsup bundle asset gates for openclaw bridge and droid runtime, with changesets and bundle output tests

Fusion-Task-Id: FN-3505

packages/dashboard/app/api.ts

@@ -5,3 +5,4 @@
  * while implementation lives under `app/api/*` modules.
  */
 export * from "./api/legacy";
+export * from "./api-node";