geo_sf_bind: Bind multiple sf objects into a single sf
Description
This internal helper takes a list of sf objects, aligns their columns,
and binds them together into a single sf object. It removes NULL or empty
objects and handles nested lists of sf.
Usage
geo_sf_bind(sf_list)
Value
A single sf object containing all input features, or NULL
if the input list is empty or contains no valid sf objects.