Bundled ffmpeg.wasm (MV3 extensions cannot load remote code).

ffmpeg/  @ffmpeg/ffmpeg 0.12.15, dist/esm  - MIT License
core/    @ffmpeg/core   0.12.10, dist/esm  - GPL-2.0-or-later (FFmpeg with libmp3lame, x264, etc.)

Sources: https://github.com/ffmpegwasm/ffmpeg.wasm and https://ffmpeg.org
Update: npm pack @ffmpeg/ffmpeg @ffmpeg/core, then copy the dist/esm files here.
