Adds visibility resume emissions to the four managed state hooks (`useMeshState`, `useNodes`, `useProjects`, `useManagedDockerNodes`) and establishes corresponding instrumentation test coverage, with a documentation update to the diagnostics reference covering board hook telemetry.
Fusion-Task-Id: FN-5415
- Change useMeshState to expose NodeMeshState[] and unwrap API snapshot nodes in refresh and polling flows
- Update NodesView mesh topology rendering to consume the flattened hook result directly
- Revise mesh-state and NodesView tests to validate array-based contract and topology behavior
- Document the Nodes UI mesh topology contract in architecture docs
Fusion-Task-Id: FN-3955
Implements a typed mesh snapshot API in `@fusion/core` (`CentralCore.getMeshSnapshot`, `MeshSnapshot` type) and wires it through the dashboard nodes view via a new `useMeshState` hook, substantially simplifying `MeshTopology.tsx` by replacing internal state management with the centralized snapshot.
Fusion-Task-Id: FN-3454
