fix(nix): restore native runners for darwin hash computation (#11495)

nix/node_modules.nix

@@ -2,8 +2,6 @@
   lib,
   stdenvNoCC,
   bun,
-  bunCpu ? if stdenvNoCC.hostPlatform.isAarch64 then "arm64" else "x64",
-  bunOs ? if stdenvNoCC.hostPlatform.isLinux then "linux" else "darwin",
   rev ? "dirty",
   hash ?
     (lib.pipe ./hashes.json [
@@ -16,6 +14,9 @@ let
     builtins.readFile
     builtins.fromJSON
   ];
+  platform = stdenvNoCC.hostPlatform;
+  bunCpu = if platform.isAarch64 then "arm64" else "x64";
+  bunOs = if platform.isLinux then "linux" else "darwin";
 in
 stdenvNoCC.mkDerivation {
   pname = "opencode-node_modules";
@@ -39,9 +40,7 @@ stdenvNoCC.mkDerivation {
     "SOCKS_SERVER"
   ];
 
-  nativeBuildInputs = [
-    bun
-  ];
+  nativeBuildInputs = [ bun ];
 
   dontConfigure = true;
 
@@ -63,10 +62,8 @@ stdenvNoCC.mkDerivation {
 
   installPhase = ''
     runHook preInstall
-
     mkdir -p $out
     find . -type d -name node_modules -exec cp -R --parents {} $out \;
-
     runHook postInstall
   '';