feat: fold traefik into the service widget type, remove the dedicated one

Traefik gets the same treatment as the other six services now instead
of a bespoke widget type: docker health merged with a single "Routes"
stat, via the same internal container-to-container API call
(http://traefik:8080/api/http/routers) it already used. No auth
needed, same as before.

Deleted lib/collectors/traefik.ts, lib/types/traefik-result.ts, and
components/widgets/traefik/ entirely - the generic service Widget.tsx
and ServiceWidgetResult shape cover it with zero new component code.

lib/collectors/services/base-url.ts

@@ -7,6 +7,7 @@ const SERVICE_PORTS: Record<ServiceWidget["service"], number> = {
   n8n: 5678,
   umami: 3000,
   headscale: 8080,
+  traefik: 8080,
 };
 
 export function serviceBaseUrl(widget: ServiceWidget): string {