add documentation

ui/src/hooks/useHashRoute.ts

@@ -0,0 +1,36 @@
+import { useState, useEffect, useCallback } from 'react'
+
+export type Route = 'app' | 'docs'
+
+interface HashRouteState {
+  route: Route
+  section: string | null
+  navigate: (hash: string) => void
+}
+
+function parseHash(hash: string): { route: Route; section: string | null } {
+  const cleaned = hash.replace(/^#\/?/, '')
+  if (cleaned === 'docs' || cleaned.startsWith('docs/')) {
+    const section = cleaned.slice(5) || null // Remove 'docs/' prefix
+    return { route: 'docs', section }
+  }
+  return { route: 'app', section: null }
+}
+
+export function useHashRoute(): HashRouteState {
+  const [state, setState] = useState(() => parseHash(window.location.hash))
+
+  useEffect(() => {
+    const handleHashChange = () => {
+      setState(parseHash(window.location.hash))
+    }
+    window.addEventListener('hashchange', handleHashChange)
+    return () => window.removeEventListener('hashchange', handleHashChange)
+  }, [])
+
+  const navigate = useCallback((hash: string) => {
+    window.location.hash = hash
+  }, [])
+
+  return { ...state, navigate }
+}