Fix .gitignore to only exclude root android/ and ios/ (Expo prebuild output) while keeping modules/ native code. Add Android WallpaperService Kotlin sources, GLSL shaders, manifest, and Gradle config.
WallpaperService with OpenGL ES 2.0 rendering, 6 GLSL fragment shaders, gyroscope integration, frame capping at 24fps with visibility-based pause. Expo Module API bridge for config persistence and system wallpaper picker launch.
