Image import wizard — additional conversion algorithms (reach 5+)

[BernardJen]

Summary

Extend the image import wizard (#11) with the remaining conversion algorithms so the wizard offers at least 5 total.

Scope

Add (final list TBD during design):

• Crosshatch (multi-angle hatching by tone)
• Dithering / stippling (dots)
• Contour / iso-level lines
• Centerline / skeleton tracing (bonus)

Each algorithm:

• Plugs into the existing wizard shell from Image import wizard — shell + adjust step + 2 algorithms #11.
• Has a live preview and exposes its key parameters.

Acceptance criteria

• Wizard offers at least 5 selectable algorithms total (including the 2 from Image import wizard — shell + adjust step + 2 algorithms #11).
• Each new algorithm has live preview + tunable params.
• Output is added as objects into the scene.

Notes

• Depends on Image import wizard — shell + adjust step + 2 algorithms #11 (wizard shell).
• Part of epic [Epic] Editor feature set: object model, pens, image import, projects #10.