Editor: remove tiles from painted zones, scrollable zone list

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lang/en.lang

@@ -1205,6 +1205,7 @@ ed.level = Level
 ed.zone_shape = Shape of a new zone
 ed.zone_new_name = Name of a new zone
 ed.zones = Zones
+ed.zone_erase = Remove tiles
 ed.shape.rect = Rectangle
 ed.shape.circle = Circle
 ed.shape.tiles = Tiles