Node shape is not reflected in sidebar or legend

If you customize the node shape, the sidebar and legend will still be a circle.

This is confusing and breaks the illusion that the node is being rendered in the side bar.

## Potential solution

* Use SVG to render a sample of the node with the appropriate color, icon, and shape inside `VertexSymbol`

Start at the VertexSymbol component and trace how the sidebar and legend render node samples. Confirm how the customized node color, icon, and shape are supplied, then verify visually that both areas reflect the configured node instead of always showing a circle.

Written by the indexing model from the issue text.