move contexts all out in own toplevel dir

- rename wizard to book

context/user.tsx

@@ -0,0 +1,9 @@
+import React from 'react'
+import { UserData } from '../lib/session'
+
+const UserContext = React.createContext<UserData>({
+  username: undefined,
+  role: undefined,
+})
+
+export default UserContext