docs(coding-agent): update README-NEW.md, tui.md, add new docs
- README-NEW.md: add environment variables, philosophy extras (no built-in to-dos, no background bash), session ID support, pi config command, plain git URLs, version pinning
- tui.md: fix hooks->extensions terminology, update Component interface (invalidate required, add wantsKeyRelease)
- Add new docs: settings.md, development.md, json.md
- Add screenshots: tree-view.png, doom-extension.png
Mario Zechner