Add `collide` kwarg to Grid.find_path() and Grid.get_dijkstra_map() that
treats entities bearing a given label as impassable obstacles via
mark-and-restore on the TCOD walkability map. Dijkstra cache key now
includes collide label for separate caching. Add Entity.find_path()
convenience method that delegates to the grid.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
