feat(ui): popovers, tooltips, progress; the render3d backend installs itself; duplicate names caught first

- `popover`: a top layer that keeps the pointer and the keyboard, closed by a press outside or Esc.
- `title` tooltips after half a second's rest, styled by .ui-tooltip.
- `<progress>` and `<meter>`.
- Atlases take rows and number cells, and importing ludic.ui/render3d.ludic is enough to draw with
  render3d.
- The compiler reports two declarations of one name before it type-checks, so a package global
  clashing with a program's reads as that, not as 29 type errors.

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

packages/ludic.ui/node.ludic

@@ -103,5 +103,6 @@ export property UiNode {
   anim_loop: bool = false
   anim_alt: bool = false
   tr_dur: float = 0.0           # transition: how long a change of opacity takes
+  popover: bool = false         # drawn on the top layer; a press outside it or Esc closes it
 }