fix(setup): enable scrolling on mobile setup page

- Change outer container from items-center to items-start sm:items-center for mobile-first layout
- Add overflow-y-auto and max-h-dvh constraints to inner content div on mobile
- Desktop (sm breakpoint) retains centered layout with no scroll constraint
- Fixes issue where setup page content exceeds viewport on mobile without zoom

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

ui/web/src/pages/setup/setup-layout.tsx

@@ -4,8 +4,8 @@ export function SetupLayout({ children }: { children: React.ReactNode }) {
   const { t } = useTranslation("setup");
 
   return (
-    <div className="flex min-h-dvh items-center justify-center bg-background px-4 py-8">
-      <div className="w-full max-w-2xl space-y-6">
+    <div className="flex min-h-dvh items-start justify-center bg-background px-4 py-8 sm:items-center">
+      <div className="w-full max-w-2xl space-y-6 overflow-y-auto max-h-dvh sm:max-h-none">
         <div className="text-center">
           <img src="/goclaw-icon.svg" alt="GoClaw" className="mx-auto mb-4 h-16 w-16" />
           <h1 className="text-4xl font-bold tracking-tight">GoClaw Setup</h1>