feat: add gateway setup wizard and fix test suite

New zt-gateway-setup script with subcommands for configuring this
router as a ZeroTier exit gateway: bridge, routing (tables 100/101),
DHCP, hotplug, and persistence. Exposes setup ubus method via backend
with ACL and LuCI panel in overview.

Also fixes two pre-existing test issues:
- overview.spec.ts: active gateway radio is intentionally enabled
  (users need to re-trigger switch for the already-selected gateway)
- drain.spec.ts: stubs drain status via page.route() since Docker
  has no real conntrack entries; fixed Playwright glob pattern bug
  where **/ubus* fails to match /ubus/?timestamp (regex needed)

mise.toml

@@ -89,6 +89,8 @@ echo "==> Uploading files..."
 
 # root/ files → strip leading root/, map to / on device
 scp -O -q root/usr/sbin/zt-gateway-switch                  "$HOST:/usr/sbin/"
+scp -O -q root/usr/sbin/zt-gateway-setup                   "$HOST:/usr/sbin/"
+echo "    zt-gateway-setup"
 echo "    zt-gateway-switch"
 scp -O -q root/usr/share/rpcd/ucode/zt-gateway.uc           "$HOST:/usr/share/rpcd/ucode/"
 echo "    rpcd/ucode/zt-gateway.uc"
@@ -109,8 +111,7 @@ scp -O -q htdocs/luci-static/resources/view/zt-gateway/overview.js  "$HOST:/www/
 echo "    overview.js"
 
 echo "==> Setting permissions..."
-ssh -q "$HOST" chmod +x /usr/sbin/zt-gateway-switch
-
+ssh -q "$HOST" chmod +x /usr/sbin/zt-gateway-switch /usr/sbin/zt-gateway-setup
 echo "==> Restarting rpcd and uhttpd..."
 ssh -q "$HOST" /etc/init.d/rpcd restart
 ssh -q "$HOST" /etc/init.d/uhttpd restart