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/api-client.js

@@ -0,0 +1,57 @@
+/**
+ * ApiClient - Handle communication with content API
+ */
+export class ApiClient {
+    constructor(options = {}) {
+        this.baseUrl = options.apiEndpoint || '/api/content';
+        this.siteId = options.siteId || 'default';
+    }
+    
+    async getContent(contentId) {
+        try {
+            const response = await fetch(`${this.baseUrl}/sites/${this.siteId}/content/${contentId}`);
+            return response.ok ? await response.json() : null;
+        } catch (error) {
+            console.warn('Failed to fetch content:', contentId, error);
+            return null;
+        }
+    }
+    
+    async updateContent(contentId, content) {
+        try {
+            const response = await fetch(`${this.baseUrl}/sites/${this.siteId}/content/${contentId}`, {
+                method: 'PUT',
+                headers: {
+                    'Content-Type': 'application/json'
+                },
+                body: JSON.stringify({ value: content })
+            });
+            
+            return response.ok;
+        } catch (error) {
+            console.error('Failed to update content:', contentId, error);
+            return false;
+        }
+    }
+    
+    async createContent(contentId, content, type) {
+        try {
+            const response = await fetch(`${this.baseUrl}/sites/${this.siteId}/content`, {
+                method: 'POST',
+                headers: {
+                    'Content-Type': 'application/json'
+                },
+                body: JSON.stringify({ 
+                    id: contentId, 
+                    value: content,
+                    type: type 
+                })
+            });
+            
+            return response.ok;
+        } catch (error) {
+            console.error('Failed to create content:', contentId, error);
+            return false;
+        }
+    }
+}