[Feature request] Add Lasso variant for UI Stamp icon stamps

### Description

The **UI Stamp** icon variants currently support Pin and Bracket annotation styles. Add a Lasso variant for icon stamps, giving users a third option for highlighting UI elements with icon-based annotations.

### Use case

Lasso-style annotations are useful when you need to call out irregularly shaped or grouped UI elements that don't fit neatly within a pin or bracket. This approach is similar to how Microsoft's annotation components handle icon stamps.

Start in the Figma library by reviewing the existing UI Stamp Pin and Bracket variants and how their icon stamps are organized. Add a Lasso variant consistent with those styles, supporting irregular or grouped UI-element highlighting. Done means UI Stamp offers Pin, Bracket, and Lasso options.

Written by the indexing model from the issue text.