Copy and impove `home-manager` module integration from `nix-on-darwin` for `nixos`
Add `homix` *server* with NVIDIA drivers, `wayland` + `river`, Jellyfin, etc.
Place all configurations in `machines/${manager}/${system}/${hostname}/...`:
- `${manager}` - One of `nixos`, `nix-on-droid`, `nix-darwin` or `home-manager`
- `${system}` - A system's architecture (can be many)
- `${hostname}` - A system's hostname (can be many)
The flake now automatically generates the needed configurations based on the above structure.
It only generates configurations for valid directory structures:
- It wouldn't generate a NixOS config if there isn't a `configuration.nix` file
- ...
