Dara's ruling: the A Teleporter entrance and its exit pocket by Elbow are
walls in the cone model. The teleporter line in the map art already shows
the link, and nobody stands in the doorway. Both bases anchor to the floor
on attack and defense, and the holdout list is empty again.

Adds tool/svg_map_crop_test.dart, which crops the bundled map art and
callouts around SVG points so a reported spot can be checked against the
drawn map without opening the app.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>