standpoint.webgui module
The single-page Standpoint GUI as one self-contained HTML string.
No build step, no framework, no npm: vanilla JavaScript + Tailwind (Play CDN) +
vega-embed (to render the Vega-Lite spec live in the browser) + marked (to render the
Markdown analysis). standpoint.api serves this at GET /gui.
Kept as a Python string (rather than a static file) so it ships inside the package: the whole GUI is a two-file backend plus this one-string frontend.