fix(ui): move overscroll-behavior from * to html (wheel scroll trap)

Same bug as cuidecar/cccb43a: \`overscroll-behavior: none\` applied to
the universal selector killed wheel events on every overflow:hidden
container on the page — hero, demo-dashboard, cta, surfaces, anything
with rounded cards. Combined with the mesh-stream overflow-y-auto
(fixed in 701516b) this was double-trapping the wheel.

Move the rule from \`*\` to \`html\`, change to \`overscroll-behavior-y\`.
Still prevents rubber-band chaining at the document level, but lets
wheel events propagate naturally through nested overflow containers.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/ui/web/src/styles/globals.css

@@ -87,11 +87,11 @@
 @layer base {
   * {
     @apply border-border outline-ring/50;
-    overscroll-behavior: none;
   }
 
   html {
     scroll-behavior: smooth;
+    overscroll-behavior-y: none;
   }
 
   body {