feat: complete code cleanup and create feature parity plan

Major Architecture Improvements:
- Separate JavaScript library (lib/) with proper build system
- Go CLI with embedded library using go:embed
- Hot reload development with Air integration
- Library + CLI build pipeline with npm run build

Code Cleanup:
- Remove obsolete assets (insertr-cli/assets/editor/)
- Clean up package.json metadata and dependencies
- Update .gitignore for new architecture
- Remove unused 'marked' dependency

New Documentation:
- Add comprehensive TODO.md with feature gap analysis
- Document critical gaps between prototype and current library
- Create phased implementation plan for feature parity
- Update DEVELOPMENT.md with hot reload workflow
- Add LIBRARY.md documenting new architecture

Hot Reload System:
- Air watches both Go CLI and JavaScript library
- Library changes trigger: rebuild → copy → CLI rebuild → serve
- Seamless development experience across full stack

Next Steps:
- Current library is basic proof-of-concept (prompt() editing)
- Archived prototype has production-ready features
- Phase 1 focuses on professional forms and authentication
- Phase 2 adds validation and content persistence

.gitignore

@@ -7,6 +7,9 @@ yarn-error.log*
 # Build outputs
 dist/
 build/
+lib/dist/
+insertr-cli/insertr
+insertr-cli/tmp/
 
 # Environment files
 .env
@@ -49,7 +52,7 @@ temp/
 # Optional REPL history
 .node_repl_history
 
-# Go specific (for future backend)
+# Go specific
 *.exe
 *.exe~
 *.dll
@@ -59,6 +62,7 @@ temp/
 *.out
 go.work
 vendor/
+insertr-cli/build-errors.log
 
 # Database files
 *.db