update nix & project files to use mold

shell.nix

@@ -1,15 +1,23 @@
-{ pkgs ? import <nixpkgs> { } }:
+{ pkgs? import <nixpkgs> { } }:
 
 with pkgs;
 
 mkShell rec {
+  # Tools needed to build the project
   nativeBuildInputs = [
     pkg-config
+    # Add the wrapped mold linker
+    mold-wrapped
+    # Add clang, needed to drive mold via -fuse-ld=
+    llvmPackages.clang # Or just `clang`
   ];
+
+  # Libraries the project links against or needs at runtime
   buildInputs = [
     udev alsa-lib vulkan-loader
     xorg.libX11 xorg.libXcursor xorg.libXi xorg.libXrandr # To use the x11 feature
     libxkbcommon wayland # To use the wayland feature
   ];
+
   LD_LIBRARY_PATH = lib.makeLibraryPath buildInputs;
 }