Add src/ui/calendar.md with full documentation for both calendar
namespaces (picker props, event grid, ticker, agenda, event data
format, date utilities, CSS classes).
Add a minimal markdown-to-hiccup renderer (ui.markdown) that handles
headings, fenced code blocks, tables, lists, inline code, and bold.
Styled with ui/markdown.css using theme tokens.
Each dev target renders the docs inline on the Calendar page:
- Hiccup: slurps the .md file at render time
- Replicant: embeds via compile-time macro (ui.macros/inline-file)
- Squint: fetches from /calendar.md served by Vite
Also fixes calendar event grid day cells to be square (aspect-ratio: 1
with overflow: hidden instead of min-height).
d6d205cb3b