Wraps GraphController + GraphView into the panel widget: loads the vault
graph on mount, shows a spinner / empty / error state until it is ready,
then draws the graph and opens a note on node click via editor.open. A
debounced refresh keeps the current graph on screen instead of flashing
back to the spinner.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>