Replace manual nginx unprivileged configuration with the official nginxinc/nginx-unprivileged image which handles non-root execution properly out of the box. Benefits: - No need for complex nginx configuration hacks - Proper temp directory handling - Officially maintained by NGINX Inc - Removes need for UID/GID configuration in docker-compose Changes: - Dockerfile: Use nginxinc/nginx-unprivileged:alpine-slim - Removed manual nginx temp dir configuration - Simplified docker-compose.yml (removed user directive) - Updated .env.example and README - Updated image size estimate in docs