Interactive Geometry Drawing in Lonboard

**Is your feature request related to a problem? Please describe.**
In some demo notebooks, I want users to be able to draw polygons (e.g., AOIs) interactively. Currently, I use `ipyleaflet`’s `DrawControl`, but it requires extra installation steps and breaks the flow when trying to keep dependencies minimal and use Lonboard exclusively.

**Describe the solution you'd like**
Support basic interactive geometry drawing (starting with polygons) directly within Lonboard maps in notebooks. Ideally, the tool would emit GeoJSON output or support a callback for accessing drawn features.

**Describe alternatives you've considered**
I’ve used `ipyleaflet`, which works well but adds unnecessary complexity when Lonboard is already used for visualization. Exporting geometry separately and uploading it to the notebook is also possible, but it breaks the interactivity.

**Additional context**
Reference: [`ipyleaflet.GeomanDrawControl`](https://ipyleaflet.readthedocs.io/en/latest/controls/geoman_draw_control.html) shows the kind of lightweight functionality that would be helpful. Even minimal polygon drawing would unlock essential use cases in educational and exploratory workflows.