refactor: consolidate all Node.js development into lib package

- Move scripts/ to lib/scripts/ and convert to ESM modules
- Consolidate dependencies: add live-server to lib/package.json
- Remove root package.json and node_modules split
- Preserve CLI integration via existing rebuild-library.sh
- Add development quickstart guide for new unified workflow
- Clean up outdated file references and duplicate assets

TODO.md

@@ -100,6 +100,9 @@ Bring the current library (`lib/`) up to feature parity with the archived protot
 - [ ] Adaptive modal sizing and positioning
 - [ ] Touch-optimized hover states
 
+#### 3.3 Server / CLI
+- [ ] A better way to inject insertr.js library into our CLI. Maybe use a cdn when library is stable.
+
 ## Key Files to Port/Adapt
 
 ### From Prototype (`demo-site/archive/insertr-old/`)
@@ -143,4 +146,4 @@ Keep the current library + CLI architecture while porting prototype features:
 
 ---
 
-*This TODO represents bringing a basic proof-of-concept up to production-ready feature parity with the original prototype.*
+*This TODO represents bringing a basic proof-of-concept up to production-ready feature parity with the original prototype.*