Features:
• Auto-save: Layout saves automatically 500ms after any change
• Manual Save: Click "Save Now" to force immediate save
• Export/Import: Download layout as JSON or upload a saved layout
• Reset: Restore default layout with confirmation
• Edit mode: Drag widgets to move, drag green dots to resize
• Add widgets from library (left side), hover for delete/settings controls
• Watch the event log below to see all persistence operations