feat(ui): number and key fields, notes, anchored popovers, text-shadow, and pictures as painted

- <input type="number" min max step>: typed digits replace its value (a minus when min allows one,
  a point when step has a fraction), Enter or leaving the field commits them held between min and
  max, the left and right arrows step it.
- <input type="key">: Enter or a click starts it listening and the next key is its value, Tab, the
  arrows and Enter included; Esc stops it listening, Backspace clears it, `shown` names the value,
  and ui_capturing() tells the host to leave its keys alone (through the frame that ended it).
- note="..." under any control's label (.ui-labels > .ui-label + .ui-note); a range's (or number's)
  value with decimals, format="percent" and a unit.
- A popover with `anchor="id"` (the nearest element of that id) or a bare `anchor` (the element
  before it) sits beside it by `placement` (right, left, bottom, top), its margin the gap, opens to
  the other side where it would leave the screen, and is kept on it.
- A tooltip's title splits into lines at a newline or a written \n.
- text-shadow, inherited, drawn sharp under the text.
- ui_opacity(): the group opacity a native's draw is at.
- border-image is drawn as painted with no background colour, tinted by one, and not at all when
  that colour is transparent (it drew a white nine-slice).
- A picture file is drawn untinted, as a browser draws one; an atlas cell (prefix:name) still takes
  the color around it, and an <img> with its own color is tinted by it.
- The render3d backend loads a picture again when its file changes or appears (a failed load was
  kept for ever), and at once after ui_image_reload(path); takes a path with a drive letter (C:/...)
  as a path rather than an atlas; and slices a nine-slice by its texture's own width and height.
- ui_inputs.ludic and ui_look.ludic; LANGUAGE.md and the changeset say all of it.

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

packages/ludic.ui/draw_content.ludic

@@ -0,0 +1,61 @@
+# draw_content.ludic - what is inside a box drawn: a text's lines, placed by text-align, each over its
+# text-shadow, and a picture
+# a text's lines (one, or the wrapped ones), each placed by text-align, the last cut by an ellipsis
+function fr_text(n: UiNode) -> void {
+  let y = n.y + n.pt + n.bt
+  let a = n.rfg_a * fr_ga
+  let sh = fr_text_shadow(n)
+  if n.lines == null {
+    var s = n.text
+    if n.ellipsis { s = ly_ellipsis(s, n.rsize, n.cw - ly_hin(n)) }
+    fr_line(n, sh, fr_line_x(n, s), y, s, a)
+    return
+  }
+  for i in 0 .. len(n.lines) { fr_line(n, sh, fr_line_x(n, n.lines[i]), y + float(i) * n.rsize * 1.25, n.lines[i], a) }
+}
+# one line, over its shadow when it has one
+function fr_line(n: UiNode, sh: UiNodeX, x: float, y: float, s: string, a: float) -> void {
+  if sh != null { ui_be.text(x + sh.tsh_x, y + sh.tsh_y, s, n.rsize, sh.tsh_c, sh.tsh_a * fr_ga) }
+  ui_be.text(x, y, s, n.rsize, n.rfg, a)
+}
+# text-shadow is inherited: the nearest element that says it, or null (none)
+function fr_text_shadow(n: UiNode) -> UiNodeX {
+  var at = n
+  while at != null {
+    if at.ex != null and at.ex.tsh_set {
+      if at.ex.tsh_c < 0 { return null }
+      return at.ex
+    }
+    at = at.parent
+  }
+  return null
+}
+# the opacity a native's draw is at: every group opacity around it, its own included
+export function ui_opacity() -> float { return fr_ga }
+# where a line starts: text-align within the room the box gives it
+function fr_line_x(n: UiNode, s: string) -> float {
+  let x = n.x + n.pl + n.bl
+  if n.talign == UI_START { return x }
+  let spare = n.cw - ly_hin(n) - ly_text_w(s, n.rsize)
+  if n.talign == UI_CENTER { return x + spare / 2.0 }
+  return x + spare
+}
+# an <img>: a picture file drawn as it is, as a browser draws one (unless the img sets its own
+# color); a cell of an atlas ("icon:tent") is a glyph, and takes the color around it as text does
+function fr_image(n: UiNode) -> void {
+  var c = 16777215
+  var a = fr_ga
+  if n.fg != UI_INHERIT or fr_is_cell(n.src) {
+    c = n.rfg
+    a = fr_ga * n.rfg_a
+  }
+  ui_be.image(n.src, n.x + n.pl + n.bl, n.y + n.pt + n.bt, n.cw - ly_hin(n), n.ch - ly_vin(n), c, a)
+}
+# prefix:name, and not a path (C:/... is a drive, not an atlas)
+function fr_is_cell(src: string) -> bool {
+  for i in 0 .. len(src) {
+    if src[i] == 47 or src[i] == 92 { return false }
+    if src[i] == 58 { return i > 1 }
+  }
+  return false
+}