- Render Mermaid diagrams in the generated docs: a `mermaid` fenced code block now becomes a themed SVG diagram, with properties set on the opening fence - `placement` puts the interactive controls in any corner (`top-left`, `top-right`, `bottom-left`, `bottom-right`; default `bottom-right`) and `actions` shows or hides them, overriding the default of appearing only once a diagram is taller than 120px. Readers can zoom, pan, drag the diagram with the mouse, reset the view, and open it full screen. Diagrams are rendered at build time by `beautiful-mermaid` inside a `server-only` module, so pages stay `force-static` and neither the library nor its elkjs layout engine reaches the browser (they would otherwise add roughly 537 KB gzip to the client bundle); the client ships only the zoom/pan chrome. Diagram colors resolve through new `--mermaid-*` CSS custom properties derived from the site palette, so one build-time render serves both modes and the theme toggle recolors diagrams through the cascade with no re-render, and any of them can be overridden to restyle diagrams without touching the palette
- Support six Mermaid diagram types - flowchart, sequence, state, class, entity relationship, and XY chart - and degrade the rest gracefully: `beautiful-mermaid` is an independent implementation rather than a Mermaid wrapper, so `pie`, `gantt`, `mindmap`, `journey`, and `gitGraph` are unsupported and throw, as does any syntax error. Because doc pages are statically rendered, an uncaught throw would fail the whole page's build, so an unrenderable diagram now falls back to a plain code block showing its source and logs a warning naming the offending file, letting a build always finish. ELK is the layout engine for every diagram, and a `%%{init: ...}%%` directive is read as a comment and ignored rather than erroring, so diagrams ported from other tools still render. A new Mermaid documentation page covers the syntax, the supported types, the properties, and the theming variables
- Carry a fenced code block's meta string (the text after the language on the opening fence) through to the component that renders it: `mdast-util-to-hast` drops it when building ``, so a new rehype plugin copies it onto the code element, where MDX passes it through as a plain string that is parsed rather than evaluated
- Redesign the generated site's header logo as a white mascot on a solid blue circle, and keep the rest of a logo correctly themed: the header's fill override now targets any element carrying a `fill` attribute instead of only `path`, so non-path SVG shapes (`circle`, `rect`, `g`) also pick up the primary theme color, while the mascot artwork is marked `ignore-fill` and excluded from that override so it stays white rather than being recolored
- Add a "What is Doccupine" page to the Getting Started section of the starter documentation
- Add generated app dependency beautiful-mermaid ^1.1.3, and update @langchain/core to ^1.2.3, posthog-js to ^1.403.0, posthog-node to ^5.45.1, @typescript-eslint/eslint-plugin and @typescript-eslint/parser to ^8.64.0, and tsx to ^4.23.1