fix(neovim): support mason tools on nixos

Manages `~/.pi/agent` config via the itme-brain/pi submodule and
provides nodejs_20 with NPM_CONFIG_PREFIX=~/.npm-global so pi and its
extensions install via the global npm ecosystem.

Pi itself and extensions like pi-mcp-adapter are installed manually
via `npm install -g` rather than packaged through nix — the ecosystem
moves too fast to keep derivations current.

system/machines/desktop/default.nix

@@ -11,6 +11,7 @@
     ../../keys
     ../../modules/sops
     ../../modules/docker
+    ../../modules/nix-ld
     ./hardware.nix
     ./system.nix
   ];

system/machines/server/default.nix

@@ -10,6 +10,7 @@
     ../../../user
     ../../keys
     ../../modules/sops
+    ../../modules/nix-ld
     ./hardware.nix
     ./system.nix
   ];

system/machines/wsl/default.nix

@@ -10,6 +10,7 @@
     ../../../user
     ../../keys
     ../../modules/sops
+    ../../modules/nix-ld
     ./system.nix
   ];
 }

system/modules/nix-ld/default.nix

@@ -0,0 +1,39 @@
+{ pkgs, lib, config, ... }:
+
+with lib;
+let
+  cfg = config.modules.system.nix-ld;
+
+in
+{
+  options.modules.system.nix-ld = {
+    enable = mkOption {
+      type = types.bool;
+      default = any
+        (user: user.modules.user.neovim.enable or false)
+        (attrValues config.home-manager.users);
+      description = "Enable nix-ld so Mason-installed Neovim tools can run on NixOS.";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    programs.nix-ld = {
+      enable = true;
+      libraries = with pkgs; [
+        curl
+        expat
+        fontconfig
+        freetype
+        glib
+        icu
+        libgcc
+        libGL
+        libxkbcommon
+        openssl
+        stdenv.cc.cc
+        zlib
+        zstd
+      ];
+    };
+  };
+}

user/modules/neovim/nvim

@@ -1 +1 @@
-Subproject commit da6106c77470b336783951ff2bce795688e9663d
+Subproject commit f11e6a02db5cd8e4c8c1bdec0d34557ff995c32c