Add wireguard-tools to the installed-system package list

A freshly-installed box had no wg/wg-quick binary and no wg-quick@.service
unit, so wireguard.set_tunnel_enabled() would fail as soon as a box tried
to connect to a furtka-gateway. iso/overlay/packages.extra is unaffected —
that's the live-boot ISO's own package set, unrelated to what actually
lands on the installed disk.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0142mP6EqCkQKmR1xCp7zfmZ

archinstall/user_configuration.json

@@ -23,7 +23,8 @@
     "git",
     "htop",
     "curl",
-    "openssh"
+    "openssh",
+    "wireguard-tools"
   ],
 
   "profile": {