chore(ui): harden surface Tab cycling

Rebased onto current main with review follow-ups folded in.

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

src/ui/surfaceKeyboard.js

@@ -39,7 +39,11 @@ export function createSurfaceKeyboard({
       ),
     ].filter(
       (node) =>
-        !node.hasAttribute('disabled') && node.getClientRects().length > 0,
+        !node.hasAttribute('disabled') &&
+        !node.matches?.(':disabled') &&
+        !(Number(node.getAttribute?.('tabindex')) < 0) &&
+        !node.closest?.('[inert]') &&
+        node.getClientRects().length > 0,
     );
     if (!order.length) return;
     const first = order[0];