Host diagram CSS variables

Labels-versus-wires and identity-lenses host SVGs kept light Mermaid node fills after the Themed SVG runtime could apply connectome host CSS namespaces. Inline style="fill:#… !important" beat those variables.

Both diagrams were regenerated with @dev-centr/themed-svg 0.2.3 so stylesheet bindings rewrite those paints to var(--themed-svg-connectome-…) with fallbacks. Dark mode can recolor nodes once the runtime upgrades the image.