Comprehensive migration guide for the v0.3.0 release: non-breaking upgrade,
the windowed quit-key + input auto-drive behaviour changes, the draw_sprite
deprecation, and adoption recipes for the package manager, controllers, Tiled
maps, and the #75-#89 engine/language features. Linked from the README.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
