The rule only kept the class, but ShowkaseBrowserActivity instantiates it with
Class.forName(...).getDeclaredConstructor().newInstance(), so R8 was free to
strip the constructor. Also drop the AGP template comments and rename the file
to .keep, for consistency with app/proguard.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>