feat: wrap nixos-options binary with nix in PATH

The indexer requires nix-build to evaluate NixOS options.
Use makeWrapper to add nix to the binary's PATH.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

flake.nix

@@ -26,6 +26,13 @@
 
             subPackages = [ "cmd/nixos-options" ];
 
+            nativeBuildInputs = [ pkgs.makeWrapper ];
+
+            postInstall = ''
+              wrapProgram $out/bin/nixos-options \
+                --prefix PATH : ${pkgs.lib.makeBinPath [ pkgs.nix ]}
+            '';
+
             meta = with pkgs.lib; {
               description = "MCP server for NixOS options search and query";
               homepage = "https://git.t-juice.club/torjus/labmcp";