Add token expiry, edit notice, log allowlist, local-zone test; merge PLAN.md into SPECS.md

get_logs needs a unit from an allowlist (router-*, kea, unbound, networkd,
nftables, ddclient, acme, sshd, kernel). API tokens are valid for 1, 7, 30
(default) or 90 days, or without limit. The overview and the Changes page
say which token made the unapplied changes.

options.json (router://options) no longer holds the options' source paths:
they differ between builds of a release, so a router rebuilding itself
offline had to build the file and failed (found by the update test).

Web UI: panels flow into columns on wide screens and the width is no longer
capped; on phones the navigation is a menu button; the Advanced page uses
panels; VLAN dropdowns show their chosen names; the duplicate WireGuard
heading is gone.

basic: a subtest for wan -> local rules.

SPECS.md is now the only document (decisions, how each part works, and what
is not done yet); PLAN.md is gone.

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

pkgs/router-webui/templates/changes.html

@@ -3,6 +3,7 @@
 {{if .Diff}}
 <p>The saved settings differ from the confirmed (running) ones: <code>-</code> lines go away, <code>+</code> lines are new.
    Nothing is applied until you press Apply.</p>
+{{with .TokenEdit}}<p class="error">{{.}}</p>{{end}}
 <pre class="log">{{.Diff}}</pre>
 <div class="actions">
   <form method="post" action="/apply"><input type="hidden" name="csrf" value="{{$.CSRF}}"><button>Apply</button></form>