fix: Add librechat_default as external network in docker-compose

Removes need for manual docker network connect after each rebuild.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -9,3 +9,11 @@ services:
       - .env
     environment:
       - PORT=3001
+    networks:
+      - default
+      - librechat
+
+networks:
+  librechat:
+    external: true
+    name: librechat_default