0.4.1 - Linux build, separate volumes, touch control images

Separate music and effect volumes, touch control images, and a Linux build.

• Linux (Issue #23): ChaotixRecompiled-0.4.1-linux-x64.tar.gz. Unpack it and run ./ChaotixRecompiled. SDL3 and SDL_ttf are included next to the program, so nothing needs installing. It was built on Ubuntu 22.04 (glibc 2.35), so it should run on that and newer distributions. Built with 0 warnings; the 23 tests that apply on Linux pass, and the unpacked package passed the five ROM startup tests. It was tested under WSL, not on a desktop Linux machine.
• Separate volumes (Issue #24): OPTIONS has MUSIC and EFFECTS next to VOLUME.
  • While a sound effect plays, the channels it takes over from the music follow EFFECTS; everything else follows MUSIC, as does replacement music from Mods/Music.
  • With MUSIC at 0, a level is close to silent (below 60 RMS, against about 1,500 with music), and its sound effects still play.
  • VOLUME changes now take effect at once instead of after a restart.
  • At 100% the sound is bit-identical to before.
• Touch control images (Issue #25): put BMP images in Mods/Touch to reskin the on-screen buttons: dpad.bmp, a.bmp … start.bmp, button.bmp for every face button, and <name>_pressed.bmp while a button is held. 32-bit BMP keeps transparency, and a README.txt in the folder lists the names.
• Mods on Android: the Mods folder (music and touch images) is now Android/data/org.chaotixrecompiled/files/Mods, which you can reach with a file manager or a computer. Before, it was in the app's private storage.
• recomp.board: the repository now has a .recomp.json describing the project.

Thanks to @ZacOnGH, @sloppydoppies and @CooliKnucx for these requests. Everyone is listed in CREDITS.md.

Validation: all 26 CTest cases pass on the Windows (MinGW) build, including the 36,000-frame lockstep and golden-frame runs; the 138 unit tests include new ones for the volume split (channel mapping, and a ROM test that music off keeps sound effects). Touch images were checked in a screenshot of the running program. The packaged Windows build passed the five ROM startup tests with a system-only PATH. The Android APKs were not tested on a device for this release.

Downloads: Windows x64 zip, Linux x64 tar.gz, and Android APKs for arm64-v8a/x86_64 (the usual one) and armeabi-v7a (32-bit ARM, untested on a device). Both APKs use version code 14 and the same signing certificate as 0.4.0, for in-place updates.

You must supply your own Knuckles' Chaotix (Japan, USA) ROM. No ROM image or game assets are included.