Dynamic widget display based on selected Path Generator type

[D3mh4]

Adapt the Path Generator widget interface based on the selected trajectory type (Linear, Circle, Spiral).

For Linear : keep the current display with two cursors (start/end) and a connecting line.

For Circle : display only one cursor (center) and visualize the circle path as an overlay.

For Spiral : same logic — single center cursor and visual overlay of the spiral path.

This improves clarity and lays the groundwork for implementing future path types like Polyline and Polyclosed.