feat: aggregate all deployments into one single repo

[WoodenMaiden]

Relates to gama-platform/gama#30 in gama-platform/gama#30

• Global

  • Setup __site/headers.d
  • Write setup instructions
  • Reorganize actions with an entrypoint that calls many
  • Move repositories into separate repos
  • (on gama side) Do the workflow_calls

• PPA

  • Updated paths in scripts
  • Update template URLs

• Docker

  • Simplify workflow
    • single entry point
    • use tags as inputs

• Flatpak (repo for alpha pkg)

  • Update cloudflare pages instructions
  • Add .flatpakrepo file
  • setup deployment workflow

Test it on https://gama-distribution.pages.dev/