feat(ui): flex-shrink, text that wraps beside its siblings, calc(), order, and 0 as a size

- flex-shrink: a line whose children want more room than it has takes it back from those that
  shrink, in proportion to shrink times size and never below a min size, a fixed size or the
  content. A scroll box shrinks (and scrolls), and a box in a column shrinks as far as the scroll
  boxes inside it let it, so a list in a column takes the room its siblings leave with no height.
  `flex: grow shrink`, and `flex-shrink` by name.
- A row wider than its room measures its texts (and boxes without a width) again in the room the
  rest leave them, so a line wraps beside an icon.
- calc() with + - * / and brackets over px, %, em, rem, vw, vh, plain numbers and var(); a width
  or height keeps its percentage, taken of the room it is given. Lengths lists (padding, margin)
  keep a calc()'s spaces.
- `order` places a box's children without touching the tree.
- width: 0 and height: 0 are 0: an unset size is UI_AUTO now, not 0.
- A component root that is itself a component takes each user's class, style and id in turn (the
  outermost's id wins), and the rules of all their sheets are weighed by specificity together; a
  user's rule wins a tie. The parent's sheet used to override the child's whatever its specificity,
  and a middle component's sheet was lost.
- The default sheet lays .ui-track out as a row, so a range's fill is as tall as its track and a
  checked box's knob goes right; a range's thumb is centred on the fill's end.
- ui_boxes.ludic.

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

packages/ludic.ui/ua.ludic

@@ -1,4 +1,4 @@
 # ua.ludic - what every element looks like before a program styles it, as a browser's own sheet
 # does: headings sized, buttons and controls usable and plain, a focus ring. A theme overrides any
 # of it, with the same selectors or with the variables it reads.
-const UA_LSS: string = "h1 { font-size: 32 } h2 { font-size: 26 } h3 { font-size: 22 } h4 { font-size: 19 } h5 { font-size: 16 } h6 { font-size: 14 } small { font-size: 13 } hr { height: 1; width: fill; background: #808080; margin: 4 0 } scroll { width: fill; height: fill } img { width: 24; height: 24 } button { align-items: center; justify-content: center; gap: 8; padding: 6 14; background: #3a3f46; border-radius: 4 } button:hover { background: #4a5058 } button:disabled { opacity: 0.4 } :focus-visible { outline: 2px solid #ffcc55; outline-offset: 2 } input, select { align-items: center; gap: 10; padding: 6 10 } .ui-label { flex-grow: 1 } .ui-track { width: 44; height: 22; padding: 3; background: #555a60; border-radius: 11 } .ui-knob { width: 16; height: 16; background: #eeeeee; border-radius: 8 } input:checked .ui-track { justify-content: end; background: #d9a54a } input[type=range] .ui-track { width: 200; height: 8; padding: 0; border-radius: 4 } .ui-fill { height: fill; background: #d9a54a; justify-content: end; align-items: center; border-radius: 4 } .ui-thumb { width: 14; height: 14; background: #eeeeee; border-radius: 7; margin-right: -7 } .ui-value { min-width: 40 } .ui-field { width: 200; padding: 4 8; background: #202428; border: 1px solid #555a60 } .ui-caret { width: 2; height: 1.2em; background: #eeeeee } .ui-prev, .ui-next { color: #aaaaaa } progress, meter { width: 160; height: 10; background: #202428; border-radius: 5 } progress .ui-fill, meter .ui-fill { justify-content: start; border-radius: 5 } [popover] { position: absolute; z-index: 900 } .ui-tooltip { position: fixed; padding: 6 10; background: #202428; border: 1px solid #555a60; font-size: 15; z-index: 1000 }"
+const UA_LSS: string = "h1 { font-size: 32 } h2 { font-size: 26 } h3 { font-size: 22 } h4 { font-size: 19 } h5 { font-size: 16 } h6 { font-size: 14 } small { font-size: 13 } hr { height: 1; width: fill; background: #808080; margin: 4 0 } scroll { width: fill; height: fill } img { width: 24; height: 24 } button { align-items: center; justify-content: center; gap: 8; padding: 6 14; background: #3a3f46; border-radius: 4 } button:hover { background: #4a5058 } button:disabled { opacity: 0.4 } :focus-visible { outline: 2px solid #ffcc55; outline-offset: 2 } input, select { align-items: center; gap: 10; padding: 6 10 } .ui-label { flex-grow: 1 } .ui-labels { flex-grow: 1; gap: 2 } .ui-labels .ui-label { flex-grow: 0 } .ui-note { font-size: 13; color: #9aa0a6 } .ui-track { flex-direction: row; align-items: center; width: 44; height: 22; padding: 3; background: #555a60; border-radius: 11 } .ui-knob { width: 16; height: 16; background: #eeeeee; border-radius: 8 } input:checked .ui-track { justify-content: end; background: #d9a54a } input[type=range] .ui-track { width: 200; height: 8; padding: 0; border-radius: 4 } .ui-fill { height: fill; background: #d9a54a; justify-content: end; align-items: center; border-radius: 4 } .ui-thumb { width: 14; height: 14; background: #eeeeee; border-radius: 7; margin: 0 -7 } .ui-value { min-width: 40 } .ui-field { width: 200; padding: 4 8; background: #202428; border: 1px solid #555a60 } .ui-caret { width: 2; height: 1.2em; background: #eeeeee } .ui-prev, .ui-next { color: #aaaaaa } progress, meter { width: 160; height: 10; background: #202428; border-radius: 5 } progress .ui-fill, meter .ui-fill { justify-content: start; border-radius: 5 } [popover] { position: absolute; z-index: 900 } .ui-tooltip { position: fixed; padding: 6 10; background: #202428; border: 1px solid #555a60; font-size: 15; z-index: 1000 }"