General Refactoring

[0xlua]

starting point: https://youtu.be/vYc6IzKvAJQ

Some minor refactor TODOs

• in podman/default.nix: import *.container.nix
• make better use of the system variable
• replace "/home/lua" with ${config.users.users.lua.home} where possible
• docs: add setup instructions
  • add machine ssh/age key to .sops.yaml
  • secure boot: sbctl create-keys. see Full Disk Encryption, Secure Boot & Impermanence #126
• polish flake / make it easier to deploy