modules: fix consistent nixpkgs and nix-darwin injection

lib/modules/clan/default.nix

@@ -4,8 +4,6 @@
   _module.args = {
     inherit clan-core;
     inherit (clan-core) clanLib;
-    # TODO: This should be set via an option otherwise it is not possible to override
-    inherit (clan-core.inputs) nixpkgs nix-darwin;
   };
   imports = [
     ./module.nix

lib/modules/clan/module.nix

@@ -165,7 +165,6 @@ in
   config = {
     inventory.modules = clan-core.clanModules;
     inventory._legacyModules = clan-core.clanModules;
-    # Merge the meta attributes from the buildClan function
     inventory.meta = config.meta;
 
     outputs.moduleForMachine = lib.mkMerge [

lib/modules/default.nix

@@ -7,18 +7,27 @@
 }:
 rec {
   buildClan =
-    module: lib.warn "'buildClan' is deprecated. Use 'clan-core.lib.clan' instead" (clan module).config;
+    # TODO: Once all templates and docs are migrated add: lib.warn "'buildClan' is deprecated. Use 'clan-core.lib.clan' instead"
+    module: (clan module).config;
 
   clan =
     {
-      self ? lib.warn "Argument: 'self' must be set when using 'buildClan'." null, # Reference to the current flake
+      self ? lib.warn "Argument: 'self' must be set" null, # Reference to the current flake
       ...
     }@m:
+    let
+      nixpkgs = self.inputs.nixpkgs or clan-core.inputs.nixpkgs;
+      nix-darwin = self.inputs.nix-darwin or clan-core.inputs.nix-darwin;
+    in
     lib.evalModules {
       specialArgs = {
         inherit
           self
           ;
+        inherit
+          nixpkgs
+          nix-darwin
+          ;
       };
       modules = [
         m