feat: add nix-ld and LIBRARY_PATH for mason.nvim and other downloaded binaries

modules/nixos/desktop/fhs.nix

@@ -16,4 +16,30 @@
           })
     )
   ];
+
+  # https://github.com/Mic92/nix-ld
+  #
+  # nix-ld will install itself at `/lib64/ld-linux-x86-64.so.2` so that
+  # it can be used as the dynamic linker for non-NixOS binaries.
+  #
+  # nix-ld works like a middleware between the actual link loader located at `/nix/store/.../ld-linux-x86-64.so.2`
+  # and the non-NixOS binaries. It will:
+  #
+  #   1. read the `NIX_LD` environment variable and use it to find the actual link loader.
+  #   2. read the `NIX_LD_LIBRARY_PATH` environment variable and use it to set the `LD_LIBRARY_PATH` environment variable
+  #      for the actual link loader.
+  #
+  # nix-ld's nixos module will set default values for `NIX_LD` and `NIX_LD_LIBRARY_PATH` environment variables, so
+  # it can work out of the box:
+  #
+  #  - https://github.com/NixOS/nixpkgs/blob/nixos-24.05/nixos/modules/programs/nix-ld.nix#L37-L40
+  #
+  # You can overwrite `NIX_LD_LIBRARY_PATH` in the environment where you run the non-NixOS binaries to customize the
+  # search path for shared libraries.
+  programs.nix-ld = {
+    enable = true;
+    libraries = with pkgs; [
+      stdenv.cc.cc
+    ];
+  };
 }