refactor: reorganize features

modules/capabilities/niri/default.nix

@@ -5,7 +5,6 @@
 }:
 let
   repo = config.repo;
-  repoHelpers = repo.helpers;
 in
 {
   flake.modules.nixos.niri =
@@ -34,10 +33,7 @@ in
     let
       repoTheme = repo.theme.kanagawa;
       browserCommand = repo.desktop.browser.command;
-      fileManagerPackage = repoHelpers.resolvePackagePath {
-        inherit pkgs;
-        path = repo.desktop.fileManager.packagePath;
-      };
+      fileManagerPackage = pkgs.${repo.desktop.fileManager.packageAttr};
       terminalCommand = config.repo.terminal.primary.command;
       outputs = lib.mapAttrs (
         _: display:
@@ -65,13 +61,6 @@ in
       ) osConfig.meta.machine.displays;
     in
     {
-      assertions = [
-        {
-          assertion = fileManagerPackage != null;
-          message = "Unknown file manager package `${lib.showAttrPath repo.desktop.fileManager.packagePath}`.";
-        }
-      ];
-
       home.sessionVariables.NIXOS_OZONE_WL = "1";
 
       dconf.settings = {