Add an API reference page to the web UI

/apireference lists the REST operations (from the same route list and tool
schemas as the OpenAPI document) with access, parameters and a curl example
for this router. Linked from the API access page.

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

pkgs/router-webui/templates/tokens.html

@@ -3,7 +3,7 @@
 <section>
 <p>An assistant or a script can read this router's state and logs and edit its settings through an
    <a href="https://modelcontextprotocol.io">MCP</a> endpoint at <code>{{.URL}}</code> and, with the same features, a
-   REST API described by <a href="/api/openapi.json">OpenAPI</a> (<code>/api/v1/…</code>). It needs a token, sent as
+   REST API described by <a href="/api/openapi.json">OpenAPI</a> (<code>/api/v1/…</code>, see the <a href="/apireference">API reference</a>). It needs a token, sent as
    <code>Authorization: Bearer …</code>. A <strong>read</strong> token reads state and settings; a <strong>change</strong>
    token can also edit the settings. Edits are saved but never applied: you review them under
    <a href="/changes">Changes</a> and apply them yourself. Secrets are never sent, and every call is logged below.</p>