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/src/core/editor.js

@@ -0,0 +1,110 @@
+/**
+ * InsertrEditor - Visual editing functionality
+ */
+export class InsertrEditor {
+    constructor(core, options = {}) {
+        this.core = core;
+        this.options = options;
+        this.isActive = false;
+    }
+    
+    start() {
+        if (this.isActive) return;
+        
+        console.log('🚀 Starting Insertr Editor');
+        this.isActive = true;
+        
+        // Add editor styles
+        this.addEditorStyles();
+        
+        // Initialize all enhanced elements
+        const elements = this.core.getAllElements();
+        console.log(`📝 Found ${elements.length} editable elements`);
+        
+        elements.forEach(meta => this.initializeElement(meta));
+    }
+    
+    initializeElement(meta) {
+        const { element, contentId, contentType } = meta;
+        
+        // Add visual indicators
+        element.style.cursor = 'pointer';
+        element.style.position = 'relative';
+        
+        // Add interaction handlers
+        this.addHoverEffects(element);
+        this.addClickHandler(element, meta);
+    }
+    
+    addHoverEffects(element) {
+        element.addEventListener('mouseenter', () => {
+            element.classList.add('insertr-editing-hover');
+        });
+        
+        element.addEventListener('mouseleave', () => {
+            element.classList.remove('insertr-editing-hover');
+        });
+    }
+    
+    addClickHandler(element, meta) {
+        element.addEventListener('click', (e) => {
+            e.preventDefault();
+            this.openEditor(meta);
+        });
+    }
+    
+    openEditor(meta) {
+        const { contentId, contentType, element } = meta;
+        const currentContent = element.textContent.trim();
+        
+        // For now, use a simple prompt (will be replaced with proper modal)
+        const newContent = prompt(
+            `Edit ${contentType} content (ID: ${contentId}):`, 
+            currentContent
+        );
+        
+        if (newContent !== null && newContent !== currentContent) {
+            this.updateContent(meta, newContent);
+        }
+    }
+    
+    updateContent(meta, newContent) {
+        const { element } = meta;
+        
+        // Update the element content
+        element.textContent = newContent;
+        
+        // TODO: Save to backend API
+        console.log(`💾 Content updated:`, meta.contentId, newContent);
+    }
+    
+    addEditorStyles() {
+        const styles = `
+            .insertr-editing-hover {
+                outline: 2px dashed #007cba !important;
+                outline-offset: 2px !important;
+                background-color: rgba(0, 124, 186, 0.05) !important;
+            }
+            
+            [data-insertr-enhanced="true"]:hover::after {
+                content: "✏️ " attr(data-content-type);
+                position: absolute;
+                top: -25px;
+                left: 0;
+                background: #007cba;
+                color: white;
+                padding: 2px 6px;
+                font-size: 11px;
+                border-radius: 3px;
+                white-space: nowrap;
+                z-index: 1000;
+                font-family: monospace;
+            }
+        `;
+        
+        const styleSheet = document.createElement('style');
+        styleSheet.type = 'text/css';
+        styleSheet.innerHTML = styles;
+        document.head.appendChild(styleSheet);
+    }
+}