v2.3.0

Dark mode, and a Tailwind theme that reads the --rnx-* tokens. npm test
reports 907 passing, exit 0.

Added

• Dark mode. setMode('light' | 'dark' | 'system'), getMode() and
  getResolvedMode() set data-mode on <html>, save the choice in
  localStorage (rnx-mode) and follow prefers-color-scheme live in
  system mode. The default stays light. css/rnx.css gains a dark token
  block on [data-mode="dark"] and [data-theme="dark"], and a test checks
  that it overrides every colour the Tailwind theme reads and that the text
  pairs reach AA on the dark tokens. setMode also sets data-bs-theme, so
  Bootstrap 5.3's own dark styling follows. The Tailwind checkbox tick, radio
  dot and modal and drawer scrims have dark variants. (#9)

Changed

• The Tailwind theme reads --rnx-* tokens. Colours come from CSS
  variables with the old Tailwind hex as the fallback, so with nothing set the
  look is unchanged. Remapping colors.indigo in your Tailwind config no
  longer affects the theme; set the tokens instead. Tints, hover fills and
  focus rings use color-mix(), so browsers without it (Chrome 111, Safari
  16.2, Firefox 113) lose them. (#72, via #71)
• The focus ring offset follows --rnx-surface instead of white. (#9)

Fixed

• Toast dark styling in css/plugins.css used prefers-color-scheme, so it
  ignored setMode. It now follows data-mode and data-theme. (#9)
• Toast, StatCard and TopAppBar build their spacing classes as literal
  strings, so Tailwind generates them. (#71)