Add wireframe and transparent preview modes for 3D model inspection

Kromacut could add extra view modes in the 3D preview to make generated models easier to inspect.

This would be useful for development, debugging, and advanced users who want to better understand the generated geometry before exporting or printing.

Useful view modes could include:

• Normal shaded view.
• Transparent/x-ray view.
• Wireframe view.
• Optional wireframe overlay on top of the normal model.

The goal is to make it easier to inspect model shape, layer structure, edges, and possible geometry issues without changing the actual export.

This could live as a small view-mode control inside 3D mode, near the existing preview controls. It should be clearly treated as a preview/inspection option, not a print setting.

Desired outcome:
Users and developers can quickly switch the 3D preview into a wireframe or transparent mode to inspect the generated model more clearly, while STL/3MF export behavior remains unchanged.

Start by locating the existing 3D preview and its controls, then trace how the preview renders generated geometry without affecting export. The work is complete when users can switch between shaded, transparent, wireframe, and optional overlay modes while STL/3MF output remains unchanged.