* feat(nodes): add capability-based node compatibility negotiation
Each Sencho instance now exposes /api/meta with its version and supported
capabilities. When the user switches nodes, the frontend fetches this
metadata and disables features the remote node doesn't support via a
CapabilityGate overlay. Version is shown in the node switcher dropdown
and connection test results.
- Backend: CapabilityRegistry with static capability list and fetchRemoteMeta helper
- Backend: /api/meta (public) and /api/nodes/:id/meta (auth) endpoints
- Frontend: NodeContext enhanced with per-node meta caching (5min TTL)
- Frontend: CapabilityGate component with typed Capability union
- Frontend: 13 features wrapped with capability gates
- Docs: node-compatibility.mdx + OpenAPI spec updates
* fix(nodes): revert to require() for package.json version reading
The static import fails in the Docker multi-stage build because the
root package.json is not copied into the backend-builder stage. The
require() call resolves at runtime when the file is available.
Anso