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

lib/rollup.config.js

@@ -0,0 +1,30 @@
+import { nodeResolve } from '@rollup/plugin-node-resolve';
+import terser from '@rollup/plugin-terser';
+
+export default [
+  // Development build
+  {
+    input: 'src/index.js',
+    output: {
+      file: 'dist/insertr.js',
+      format: 'iife',
+      name: 'Insertr'
+    },
+    plugins: [
+      nodeResolve()
+    ]
+  },
+  // Production build (minified)
+  {
+    input: 'src/index.js',
+    output: {
+      file: 'dist/insertr.min.js',
+      format: 'iife',
+      name: 'Insertr'
+    },
+    plugins: [
+      nodeResolve(),
+      terser()
+    ]
+  }
+];