feat(checks): Fully rework lints

This is currently copied from my dotfiles. Should probably consider
using flake-parts to DRY this out.

checks/lib.nix

@@ -0,0 +1,35 @@
+{ pkgs, lib, ... }:
+{
+  mkLint =
+    {
+      name,
+      fileset,
+      checkInputs ? [ ],
+      script,
+    }:
+    pkgs.stdenvNoCC.mkDerivation {
+      inherit name;
+
+      src = lib.fileset.toSource {
+        root = ../.;
+        fileset = lib.fileset.difference fileset (
+          lib.fileset.fileFilter (
+            file: file.type != "regular" || file.name == "hardware-configuration.nix"
+          ) ../.
+        );
+      };
+
+      checkInputs = [ pkgs.nushell ] ++ checkInputs;
+
+      checkPhase = ''
+        nu -c '${script}' | tee $out
+      '';
+
+      dontPatch = true;
+      dontConfigure = true;
+      dontBuild = true;
+      dontInstall = true;
+      dontFixup = true;
+      doCheck = true;
+    };
+}