Mermaid Diagrams

Add themed diagrams that lildocs renders to static SVG during the build.

Use fenced mermaid code blocks:

```mermaid
flowchart LR
  Markdown --> Build
  Build --> StaticHTML[Static HTML]
```

Static Rendering

lildocs renders Mermaid diagrams during the build. Generated pages contain static SVG and do not load Mermaid from a CDN or require Mermaid client JavaScript.

Readers can expand a rendered diagram to fill the viewport. Diagram colors come from the active Shiki theme and follow configured light and dark themes.

Invalid Mermaid syntax fails the build with the source page and diagram number in the error message.

See Themes and styling to configure the themes used for syntax highlighting and diagrams.