Update Dockerfile

fix: set SHELL=/bin/bash so arrow keys work in terminal

fix: show hidden files in file browser (server config + frontend override)

Add Node.js 20 (npm/npx) + Bun to Dockerfile

Replace nginx+flask auth with single aiohttp proxy (fix JS chunks getting HTML 302)

Run supervisord as root, drop privileges per-program (fix APP_STARTING hang)

Fix Dockerfile layer ordering + non-root nginx/supervisor paths

Add password gate (nginx + Flask auth) in front of token-less JupyterLab

Add JupyterLab setup (Docker SDK, CPU)