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

SPECS.md

@@ -124,6 +124,7 @@ Learned along the way:
 
 - `/api/v1/…` with an OpenAPI 3.1 description at `GET /api/openapi.json` (no token: it describes the interface only). Same tokens, scopes, origin check, limits and audit log as MCP.
 - **One implementation**: each operation runs an MCP tool (`apiRoutes` in `api.go` maps method and path to a tool; query parameters or `If-Match` and the body become its arguments), and `TestOpenAPI` checks that every tool has an operation. Status, settings (`ETag` header), `PATCH /settings` (merge patch, `If-Match`; 409 when stale), `settings/check`, `changes` (GET the diff as text, DELETE to discard), `interfaces`, `dhcp-leases`, `update`, `apply-log`, `logs`, `options`.
+- **API reference** page in the web UI (`/apireference`, linked from API access): each operation with its access, parameters and a `curl` example for this router, from the same route list as the OpenAPI document. No "try it" form.
 - Errors are `{"error": "…"}` with 400 (refused or bad argument), 401, 403 (scope), 409 (stale ETag), 500.
 
 ## Interface names (confirmed)