Create customizable dashboard layout builder

[Nanle-code]

Description

Build advanced layout customization tool allowing users to create custom dashboard layouts.

Requirements

• Drag-and-drop widget organization
• Save multiple layouts
• Switch between layouts quickly
• Share layouts with others
• Import/export layouts
• Preset layouts library

Acceptance Criteria

• Can create 10+ custom layouts
• Switching is instant
• Layouts export/import correctly
• Works on mobile