fix: eliminate mobile horizontal overflow and right-side blank space

Use overflow-x: hidden + max-width: 100% on html/body to prevent
mobile viewport expansion. Cap decorative glow blobs with max-w
instead of fixed widths, and hide decorative dots on mobile.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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

@@ -89,6 +89,12 @@
     @apply border-border outline-ring/50;
   }
 
+  html,
+  body {
+    overflow-x: hidden;
+    max-width: 100%;
+  }
+
   html {
     overscroll-behavior: none;
     scroll-behavior: auto;