fix: remove nginx host port binding to resolve traefik conflict

backend/docker-compose.gemini.yml

@@ -96,8 +96,10 @@ services:
     image: nginx:alpine
     container_name: mtad-nginx-gemini
     restart: unless-stopped
-    ports:
-      - "80:80"
+    expose:
+      - "80"
+      # ports:
+      #   - "80:80"
       # - "8443:443" # SSL disabled for gemini test to avoid cert conflicts
     volumes:
       - ./nginx.gemini.conf:/etc/nginx/nginx.conf:ro