feat!(flake): update homix

Update flake (`neovim-nightly-overlay` is fixed)
Format all `.nix` files
Unify package/module argument order:
    - `inputs`, `outputs`, `lib`, `pkgs`, `config`, ...
Move Jellyfin config to a `NixOS` module (first one, yay)
Add `direnv` to `reo101-shell` modules (was used, but not defined as wanted)
    - TODO: make it optional (module config options)

lib/helpers.nix

@@ -9,8 +9,8 @@ rec {
     mapAttrs
       (file: type:
         if type == "directory"
-          then recurseDir "${dir}/${file}"
-          else type
+        then recurseDir "${dir}/${file}"
+        else type
       )
       (builtins.readDir dir);