Ninjacat Skies Core 0.5.16

The guardian themes play. Existing saves load as they are; no ids change.

• The twelve Ninjacat guardian themes now actually play on the Songkeeper Drum. In 0.5.15 each recording carried a leftover cover picture in front of its audio, and the game's music player stopped at the picture, so the drum ran silent. The recordings are now plain audio, the same sound to the millisecond, so every chart still lands on the beat.
• A new release check refuses any sound file that is not plain audio, so this cannot slip out again.

1.21.1 / NeoForge 21.1.249.