feat: add support for specialArgs to mkSystem

lib/default.nix

@@ -1,19 +1,32 @@
 { nixpkgs, home-manager, inputs, ... }:
+let
+  allOverlays = import (../overlays) { inherit nixpkgs; };
+in
 {
   # It's not really that I care about whether a system is a desktop system or
   # a server system, but moreso that I care about whether a system is headless or not.
   # I also care about things like if it's darwin, or wsl.
+  # TODO: Expand this to actually make use of extraSpecialArgs and pass special
+  # args to the relevant places.
   mkSystem = {
     hostname,
     system ? "x86_64-linux",
     users ? [],
-    extraModules ? []
+    extraModules ? [],
+    extraSpecialArgs ? {}
   }:
   let
-    hostModule = import ../hosts/${hostname} { inherit inputs; };
+    pkgs_with_overlays = import nixpkgs {
+      inherit system;
+      overlays = allOverlays;
+    };
+    hostModule = import ../hosts/${hostname} {
+      inherit inputs;
+      pkgs = pkgs_with_overlays;
+    };
     userModules = map (name:
       import ../users/${name} {
-        pkgs = nixpkgs.legacyPackages.${system};
+        pkgs = pkgs_with_overlays;
         lib = nixpkgs.lib;
       }
     ) users;
@@ -26,13 +39,18 @@
       name = name;
       value = import ../users/${name}/home.nix {
         username = name;
-        pkgs = nixpkgs.legacyPackages.${system};
+        pkgs = pkgs_with_overlays;
         lib = nixpkgs.lib;
       };
     }) homeUserNames);
   in
     nixpkgs.lib.nixosSystem {
       inherit system;
+      # pkgs = import inputs.nixpkgs {
+      #   inherit system;
+      #   overlays = allOverlays;
+      #   config = { allowUnfree = true; nvidia.acceptLicense = true; };
+      # };
       modules = [ hostModule ]
         ++ userModules
         ++ extraModules
@@ -43,5 +61,8 @@
             home-manager.users = homeUsers;
           }
         ] else []);
+      specialArgs = {
+        inherit inputs hostname;
+      } // extraSpecialArgs;
     };
 }