compose: default Traefik network to proxy

That's the actual network Traefik runs on; was defaulting to a
non-existent `traefik` network, causing "network ... could not be found".
Still overridable via TRAEFIK_NETWORK.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docker-compose.yml

@@ -43,7 +43,7 @@ services:
     labels:
       - "traefik.enable=true"
       # App is on two networks; tell Traefik which one to reach it on.
-      - "traefik.docker.network=${TRAEFIK_NETWORK:-traefik}"
+      - "traefik.docker.network=${TRAEFIK_NETWORK:-proxy}"
       - "traefik.http.routers.printhive.rule=Host(`${PRINTHIVE_HOST:-printhive.plexultra.com}`)"
       - "traefik.http.routers.printhive.entrypoints=${TRAEFIK_ENTRYPOINT:-websecure}"
       - "traefik.http.routers.printhive.tls.certresolver=${TRAEFIK_CERTRESOLVER:-letsencrypt}"
@@ -57,8 +57,8 @@ volumes:
 
 networks:
   default:
-  # The existing Traefik network (same one your other services use).
-  # Set TRAEFIK_NETWORK in Dockhand to its exact name.
+  # The existing Traefik network (the `proxy` network Traefik runs on).
+  # Override with TRAEFIK_NETWORK if it ever changes.
   traefik:
     external: true
-    name: ${TRAEFIK_NETWORK:-traefik}
+    name: ${TRAEFIK_NETWORK:-proxy}