feat(ui): ludic.ui grows toward HTML, CSS and React (Phase 0.U1-U4)

- Natives: ui_native(tag, measure, draw) makes an element the program draws itself; ui_fire
  runs its on-<event> with event.value. input, select and textarea have simple defaults.
- React:
  - keyed <each>, <let>, <provide> context through components, <fragment>;
  - named slots, default props on <component>;
  - on-mount / on-unmount;
  - inline text inside text elements.
- CSS:
  - custom properties and var();
  - position relative/absolute/fixed with insets and z-index;
  - em/rem/vw/vh and @media;
  - wrapping text and ellipsis, overflow;
  - + and ~ combinators, :nth-child(an+b), :checked, :active.
- Developing: errors with file:line, ui_errors(), ui_reload() keeping state, and an
  inspector-style ui_dump.
- view fields infer the type of a literal or a named function's result.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

changes/defaults-views-templates.md

@@ -27,6 +27,15 @@ with:
   `:hover`, `:disabled`, `:first-child`, `:last-child`, `:nth-child`, `:not` and more, weighed by
   specificity.
 
+- more CSS: custom properties and `var()`, `position` with insets and `z-index`, `em`/`rem`/`vw`/`vh`,
+  `@media`, wrapping text and ellipsis, `overflow`, `+`/`~`, `:nth-child(an+b)`, `:checked`, `:active`;
+- more React: keyed lists, `<let>`, `<provide>` context, `<fragment>`, named slots, `on-mount` and
+  `on-unmount`;
+- native elements a program draws itself (`ui_native`, `ui_fire`), and form controls;
+- errors with file and line, hot reload (`ui_reload`), and an inspector-style dump.
+
+A `view` field set to a literal or a named function's result needs no type.
+
 Screens are drawn through a registered renderer. `Value` gains a float kind.
 
 Also: