Fix staging containers failing on Windows Docker builds

Strip CRLF from entrypoint scripts in backend/frontend images, use Docker
DNS in staging nginx config, and wait for healthy app services before nginx.

Co-authored-by: Cursor <cursoragent@cursor.com>

infrastructure/docker-compose.registry.yml

@@ -85,8 +85,10 @@ services:
     image: nginx:alpine
     container_name: dyolink_nginx_staging
     depends_on:
-      - backend
-      - frontend
+      backend:
+        condition: service_healthy
+      frontend:
+        condition: service_healthy
     ports:
       - "${STAGING_HTTP_PORT:-8088}:80"
     volumes: