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>

examples/library/ui_popover_parts/Verbs.lss

@@ -0,0 +1,3 @@
+.page { width: 300px; height: 200px; gap: 4px }
+.verbs { top: 40px; left: 10px; width: 120px }
+progress { width: 200px }

examples/library/ui_popover_parts/Verbs.ludic

@@ -0,0 +1,6 @@
+# Verbs.ludic - a grid cell that opens a popover of verbs
+component Verbs {
+  state open: bool = false
+  state used: string = "none"
+  state health: int = 30
+}

examples/library/ui_popover_parts/Verbs.xml

@@ -0,0 +1,11 @@
+<div class="page">
+  <button id="cell" on-click="set open = true">Axe</button>
+  <if test="{open}">
+    <div popover class="verbs" on-close="set open = false">
+      <button on-click="set used = 'drop'; set open = false">Drop</button>
+      <button on-click="set used = 'give'; set open = false">Give</button>
+    </div>
+  </if>
+  <progress value="{health}" max="{100}"/>
+  <p title="how much is left">{used} {open}</p>
+</div>