CRITICAL: Fix section spacing to achieve perfect visual-preview parity

CRITICAL: Fix visual editor to preview parity issues

Fix properties panel behavior and add section editing

Implement realistic mobile/desktop preview modes

Fix visual editor section parsing to match preview parity

Enhance template dropdown to update both code and visual editors

Fix MJML editor toggle functionality

Add visual drag-and-drop interface to MJML editor

Fix navigation consistency: Update all nav bars to show 'New Editor' instead of 'Email Templates'

fix: Clean up navigation to remove redundant Email Templates link

feat: Improve UI to hide technical details from users

fix: Create dedicated serverless functions for MJML operations

fix: Correct API routing for Vercel serverless functions

fix: Update email-templates in public directory and add mjml-editor

trigger: Force Vercel deployment for MJML editor