Update ArmSwitcher to use full-screen modal on mobile

cgen-8bca5bd8ec054e2f91f397b728de0920

client/components/ArmSwitcher.tsx

@@ -1,6 +1,7 @@
 import { useState, useEffect } from "react";
 import { useNavigate } from "react-router-dom";
 import { Zap, X } from "lucide-react";
+import ArmSwitcherModal from "./ArmSwitcherModal";
 
 interface Arm {
   id: string;