feat(nix): disable build time models.dev fetching (#12644)

nix/opencode.nix

@@ -34,6 +34,7 @@ stdenvNoCC.mkDerivation (finalAttrs: {
   '';
 
   env.MODELS_DEV_API_JSON = "${models-dev}/dist/_api.json";
+  env.OPENCODE_DISABLE_MODELS_FETCH = true;
   env.OPENCODE_VERSION = finalAttrs.version;
   env.OPENCODE_CHANNEL = "local";
 
@@ -79,7 +80,7 @@ stdenvNoCC.mkDerivation (finalAttrs: {
     writableTmpDirAsHomeHook
   ];
   doInstallCheck = true;
-  versionCheckKeepEnvironment = [ "HOME" ];
+  versionCheckKeepEnvironment = [ "HOME" "OPENCODE_DISABLE_MODELS_FETCH" ];
   versionCheckProgramArg = "--version";
 
   passthru = {