Update traefik dashboard routing rules

Traefik uses the `/api` path for the internal api. For the dashboard to function, it needs to be routed, too.

minimal/docker-compose.yml

@@ -16,7 +16,7 @@ services:
       - --entrypoints.web.http.redirections.entrypoint.scheme=https
     labels:
       - "traefik.enable=true"
-      - "traefik.http.routers.dashboard.rule=PathPrefix(`/dashboard/`)"
+      - "traefik.http.routers.dashboard.rule=PathPrefix(`/dashboard/`)||PathPrefix(`/api`)"
       - "traefik.http.routers.dashboard.entrypoints=websecure"
       - "traefik.http.routers.dashboard.service=api@internal"
       - "traefik.http.routers.dashboard.tls=true"