Entities can now span multiple grid cells via tile_width and tile_height
properties (default 1x1). Frustum culling accounts for entity footprint,
and spatial hash queries return multi-tile entities for all covered cells.
API: entity.tile_size = (2, 2) or entity.tile_width = 2; entity.tile_height = 3
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
