Remove export JSON and DXF options from Potree viewer

[mosoriob]

Problem

The Potree viewer currently allows users to export scene data in JSON and DXF formats. We need to remove these export options to prevent unauthorized data extraction.

Tasks

• Identify and remove JSON export functionality from the Potree viewer interface
• Identify and remove DXF export functionality from the Potree viewer interface
• Ensure export buttons/menu items are completely removed from the UI
• Test that export options are no longer accessible via keyboard shortcuts or right-click menus

Acceptance Criteria

• No visible export options in the Potree viewer interface
• Export functionality is completely disabled in the code
• Users cannot export scene data in JSON or DXF formats
• All related UI elements (buttons, menu items) are removed

Files to Check

• Look for export-related code in the Potree viewer templates and JavaScript files
• Check for any export menu items or buttons in the UI components