Add the appliance web UI look, interface names, MCP and REST API, local zone

Web UI: dark/light themes (appliance layout, sidebar, switch checkboxes),
theme preference on the Advanced page, Changes page with the pending diff.

Interface names: router.interfaces.<name>.mac, lans.<l>.deviceName and
pppoe.vlanName; a rename is staged for the next reboot by router-apply.

Remote access: an MCP server (POST /mcp) and an OpenAPI REST API
(/api/v1, /api/openapi.json) with the same tokens, scopes, limits and audit
log; tools to read status, settings, leases, logs (get_logs), and to edit
and check the saved settings (never applied). Tokens on the API access page.

Firewall: a reserved `local` zone (the router itself) as the destination of
rules, so the web UI or SSH can be allowed from the WAN.

PLAN.md lists what is still left.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AeFqV9dZrK6nipHkPfyM4F

pkgs/router-webui/static/menu.js

@@ -1,11 +1,3 @@
-// Menus close on a click elsewhere; forms with data-confirm ask first.
-// Close an open menu when the click is somewhere else.
-document.addEventListener("click", function (e) {
-  document.querySelectorAll("nav details[open]").forEach(function (d) {
-    if (!d.contains(e.target)) d.removeAttribute("open");
-  });
-});
-
 // Ask before a form marked data-confirm is sent.
 document.addEventListener("submit", function (e) {
   var q = e.target.getAttribute("data-confirm");