The resource list in the sidebar currently uses a flat list of checkboxes with CSS-based indentation for nested resources, without any semantic hierarchy.
We should use the MUI X TreeView component, which provides:
- Proper ARIA tree semantics (role="tree", role="treeitem", aria-level, aria-expanded)
- Arrow key navigation between resources
- Expand/collapse for nested resources
- Checkbox selection per node for toggling resource visibility
The resource list in the sidebar currently uses a flat list of checkboxes with CSS-based indentation for nested resources, without any semantic hierarchy.
We should use the MUI X TreeView component, which provides: