refactor: replace UptimeRobot keep-alive implementation with Cloudflare Workers based solution

refactor: migrate UptimeRobot configuration from client-side dynamic form to environment variable-based monitoring

feat: enhance Cloudflare proxy with shared secret support, add uptime monitoring features, and improve startup timeout handling

refactor: standardize Cloudflare proxy implementation, clean up configuration, and update documentation

chore: rename proxy variable to CLOUDFLARE_PROXY_URL

docs: cleanup project and update documentation for universal proxy

refactor: remove python3 symlink redirection and add default N8N_LOG_LEVEL configuration

chore: disable task runners and remove unused python virtual environment initialization

feat: install python3-venv and automatically initialize a local virtual environment for n8n in start script

feat: configure n8n to use external runners mode via environment variables

chore: replace N8N_RUNNERS_ENABLED with N8N_PYTHON_NODES_ENABLED in environment configuration

refactor: optimize startup, improve security, and simplify n8n configuration for v2 compatibility

feat: add open-source files, fix critical bugs, rewrite README with Duplicate Space button