Update README.md with new features documentation (Task - Docs Updates)

- Add comprehensive command reference with all new flags:
  --dry-run, --security, --print, --config, --skip-build
- Add Security Baseline section documenting:
  - shipnode harden command
  - shipnode doctor --security audit
  - Configuration profiles with --config flag
- Add CI/CD Integration section with GitHub Actions workflow generator
- Add Deploy Preview (dry-run) documentation with example output
- Update Features list to include all new capabilities
- Organize zero-downtime deployment docs into proper section
- Remove duplicate content from troubleshooting section
- Mark Docs Updates task as completed in TODO.md

Author: Alade Yessoufou

AGENTS.md

@@ -0,0 +1 @@
+CLAUDE.md