* Add flake.lock and clean up flake.nix
Add a lockfile to work around https://github.com/NixOS/nix/issues/6541
(and because it's a good idea anyway).
Also use flake-utils, and restrict ourselves to the five platforms
supported by nixpkgs. Otherwise, the IFD for nmd fails on weird
platforms. This fixes `nix flake check`.
Remove the redundant `apps` output, see https://github.com/nix-community/home-manager/pull/2442#issuecomment-1133670487
* nixos,nix-darwin: factor out into a common module
* nixos,nix-darwin: make `home-managers.users` shallowly visible
Make sure the option is included in the NixOS/nix-darwin manual (but the
HM submodule options aren't).
Also add a static description to the HM submodule type so that we don't need to
evaluate the submodules just to build the option manual. This makes
nixos-search able to index the home-manager flake.
Also clean up some TODOs.
* flake: add nmd and nmt
This avoids having to use `pkgs.fetchFromGitLab` in an IFD, which causes
issues when indexing packages with nixos-search because `pkgs` is
instantiated with every platform.
