No support for Mermaid diagrams

[MelbourneDeveloper]

Problem

The dart_node site includes Mermaid diagram support via a script block in the base template. The plugin's base.njk has no Mermaid integration.

Expected behavior

The plugin should either:

1. Include Mermaid support out of the box (opt-in via config)
2. Provide a {% block scripts %} that sites can use to add Mermaid (it does have this, but documentation should mention it)

dart_node implementation

<script type="module">
  import mermaid from 'https://cdn.jsdelivr.net/npm/mermaid@10/dist/mermaid.esm.min.mjs';
  mermaid.initialize({
    startOnLoad: true,
    theme: document.documentElement.getAttribute('data-theme') === 'dark' ? 'dark' : 'default',
    securityLevel: 'loose'
  });
</script>

The plugin's base.njk does have {% block scripts %}{% endblock %} which can be used, but this should be documented.