Finalize electron build

[K20shores]

• [ ] add prePackage (or other stage) hook to:
  • detect host OS/arch
  • download respective release from https://github.com/indygreg/python-build-standalone/releases
  • extract archive into root directory
  • use the downloaded python to run
    • `./python/ -m pip install musica==0.6.1.dev0 acom-music-box
• [ ] error handling for undetected python
• [ ] clear update process for bundled python
  • extend dependabot?
  • github api for detecting new releases on a github project
• [ ] build our own python bundle?
  • git-submodule