Reveal a cut-off carousel item under reduced motion

Plan step 36 review of a149970d. Reduced motion writes a zero inset for
every item, so isMasked() never called one partly shown and a press on
an item the row cut off did nothing. It now reads the item's box against
the scrollport there, as it already did for multi-aspect, and the
browser test the rewrite added to document the gap asserts the reveal
instead (plan step 32's owed test).

A focused item's inset ring is 3px in again: Tailwind's
-outline-offset-3 is 3px, not the 12px the rewrite wrote.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

resources/css/components/carousel-item.css

@@ -12,8 +12,9 @@
  *
  * The item renders the shared `md-focus-ring` class (foundation/interaction.css) rather than a
  * hand-rolled ring — the box the class draws *is* the item's own whole hit area — refined here to
- * an inset ring: an item sits edge to edge with its neighbours in the row, so the class's own 2px
- * *outward* offset would draw under the next item instead of around this one.
+ * an inset ring, 3px in, its own width (the old `focus-visible:-outline-offset-3`): items sit 8px
+ * apart with the row clipping them, so the class's own 2px *outward* offset would be cut off at the
+ * row's edges and crowd the next item.
  *
  * Full-screen: edge to edge, no corner, no mask — `--material-carousel-shift`/`-inset` go unread.
  * Multi-aspect: the view writes the item's own `aspect-ratio` inline (`aspect`, a prop, held
@@ -40,7 +41,7 @@
     }
 
     [data-md-carousel-item]:focus-visible {
-        outline-offset: -12px;
+        outline-offset: -3px;
     }
 
     [data-md-carousel='full-screen'] > [data-md-carousel-scroller] > [data-md-carousel-item] {