feat(ui): nine-slice corners clamped to half the box in each direction, cut on whole pixels

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

changes/defaults-views-templates.md

@@ -94,6 +94,8 @@ What a game's screens found missing, now in `ludic.ui`:
   rule), not the one it had so far;
 - `min()`, `max()` and `clamp()`, in `calc()` or on their own; `top` / `right` / `bottom` / `left`
   as a percentage or a `calc()` of one, of the containing block;
+- a nine-slice's corners are clamped to half the box in each direction on its own and cut on whole
+  pixels (`ui_nine_cuts`), so a small key cap has no seam;
 - a transition lands exactly on its end value (it had stopped a rounding error short of it, at every
   frame rate).