Move auth and timezone hooks into dedicated hook files

frontend/src/components/RequireAuth.tsx

@@ -7,7 +7,7 @@
  */
 
 import { Navigate, useLocation } from "react-router-dom";
-import { useAuth } from "../providers/AuthProvider";
+import { useAuth } from "../hooks/useAuth";
 
 interface RequireAuthProps {
   /** The protected page content to render when authenticated. */