feat(catalyst): add useBreakpoint hook for responsive wizard layout

Missing file that was created locally but never committed.
Provides mobile/tablet/desktop breakpoint detection used across all wizard steps.

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

products/catalyst/bootstrap/ui/src/shared/lib/useBreakpoint.ts

@@ -0,0 +1,20 @@
+import { useState, useEffect } from 'react'
+
+export type Breakpoint = 'mobile' | 'tablet' | 'desktop'
+
+function getBreakpoint(): Breakpoint {
+  if (typeof window === 'undefined') return 'desktop'
+  if (window.innerWidth < 768)  return 'mobile'
+  if (window.innerWidth < 1080) return 'tablet'
+  return 'desktop'
+}
+
+export function useBreakpoint(): Breakpoint {
+  const [bp, setBp] = useState<Breakpoint>(getBreakpoint)
+  useEffect(() => {
+    const handler = () => setBp(getBreakpoint())
+    window.addEventListener('resize', handler)
+    return () => window.removeEventListener('resize', handler)
+  }, [])
+  return bp
+}