feat(ui): ludic.ui is a UI framework - input, controls, render3d backend, the CSS a game needs

A game no longer writes a host:
- The runtime reads Input itself: focus and keyboard navigation (Tab, arrows, Enter/Space,
  autofocus), the pointer (hover, :active, click on release, drag), and scroll boxes with the
  wheel, a draggable scrollbar, clipping and scroll-into-view.
- HTML's controls are built in (button, checkbox, radio, range, select, text, key capture), made
  of plain parts a stylesheet styles, each reporting with on-change and event.value.
- ludic.ui/render3d.ludic draws with render3d's overlay: textures, named atlases (icon:NAME),
  nine-slice border-image, rounded rects and rings, clipping, and a scale.
- Hooks for the program's language, sounds and clock (ui_translator, ui_sounds, ui_clock).
- ui_dev: hot reload, errors on screen, LUDIC_UI_DUMP.
- CSS:
  - colours as #rgb / #rrggbbaa / rgb() / rgba() / names;
  - border-radius and outline (following the radius), box-shadow, background-image and a tinted
    border-image;
  - group opacity, @keyframes / animation, transition;
  - :focus, :focus-visible and :focus-within.
- HTML mixed content, and boolean attributes.
- render3d gains tex_width / tex_height, and the XML reader keeps text runs in order.

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

packages/ludic.ui/index.ludic

@@ -14,7 +14,11 @@ import "env.ludic"
 import "eval.ludic"
 import "act.ludic"
 import "native.ludic"
-import "forms.ludic"
+import "controls.ludic"
+import "controls_build.ludic"
+import "input.ludic"
+import "focus.ludic"
+import "scroll.ludic"
 import "life.ludic"
 import "tpl.ludic"
 import "tpl_lines.ludic"
@@ -23,15 +27,21 @@ import "lib_util.ludic"
 import "class.ludic"
 import "instance.ludic"
 import "reload.ludic"
+import "dev.ludic"
 import "link.ludic"
 import "state.ludic"
 import "build.ludic"
 import "build_more.ludic"
 import "build_class.ludic"
 import "elem.ludic"
+import "color.ludic"
 import "attr.ludic"
 import "attr_box.ludic"
 import "attr_place.ludic"
+import "attr_edge.ludic"
+import "ua.ludic"
+import "anim.ludic"
+import "transition.ludic"
 import "units.ludic"
 import "style.ludic"
 import "style_rule.ludic"
@@ -48,4 +58,5 @@ import "frame.ludic"
 import "pointer.ludic"
 import "screen_class.ludic"
 import "draw.ludic"
+import "draw_order.ludic"
 import "dump.ludic"