Replacing the FFmpeg libraries in Lumenoir 1.0.0 (arm64-v8a)

1. Build FFmpeg (modified or not) with build_ffmpeg.sh, keeping the same SONAMEs
   (libavutil.so, libswresample.so, libavcodec.so) and an ABI compatible with FFmpeg 9.0.
   If the ABI changes, rebuild libffmpegJNI.so from glue/src/main/jni (CMakeLists.txt).
2. Copy the Lumenoir APK from your headset: adb shell pm path app.lumenoir.player, then adb pull.
3. Replace lib/arm64-v8a/libavcodec.so, libavutil.so and libswresample.so (and libffmpegJNI.so if rebuilt)
   inside the APK, then align and sign it with your own key:
   zipalign -p -f 4 in.apk aligned.apk ; apksigner sign --ks your.keystore aligned.apk
4. Uninstall the store version and install yours with adb install aligned.apk (developer mode).
   A copy signed with another key plays your videos normally. Premium is tied to the copy signed
   by the publisher and bought through the Meta Horizon Store, so it is not available on it.

Questions: contact@lumenoir.app
