Host diagram fills follow dark mode

Host Mermaid diagrams kept light-theme node fills after the Themed SVG runtime could apply dark host CSS namespaces. Inline Mermaid style="fill:#… !important" beat the namespaced stylesheet variables.

Diagrams were regenerated with @dev-centr/themed-svg 0.2.2 so stylesheet bindings rewrite those inline paints to var(--themed-svg-ftn-diagram-…) with fallbacks. Dark mode now recolors nodes when the runtime upgrades the image.