Port the neumorphic theme to daisyUI themes and Tailwind utilities

Styles/theme.css defines two daisyUI themes, neo-light (default) and neo-dark
(prefersdark). Every colour is an hsl() of three runtime variables:
--neo-hue-light, --neo-hue-dark and --neo-chroma. One formula replaces the six
hard-coded branches CascadingState writes today. Chroma 0 gives the grey themes,
and the fallbacks match PageSettings' defaults.

Styles/neo.css ports neomorph.scss:
- neo-raised, neo-inset and neo-flat, with sizes neo-2xs, neo-xs, neo-sm and
  neo-md. The size variables don't inherit, and Tailwind variants replace the
  old -sm..-2xl classes, some of which were never compiled.
- The pressed and raised gradients, and the rainbow hue-slider track.
- @utility overrides that give the neumorphic look to daisyUI's buttons, fields,
  selectors and surfaces. They sit above daisyUI's own cascade layers, so each
  one leaves out the variants it must not touch: ghost, link, outline and the
  rest.

Styles/base.css carries over base.scss: scrollbars, selection colours, the
focus outline reset, and link underlines everywhere except on buttons.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

Styles/app.css

@@ -9,3 +9,7 @@
 	themes: false;
 	logs: false;
 }
+
+@import "./theme.css";
+@import "./neo.css";
+@import "./base.css";