fix: keep response-file temp file for downstream steps

The temporary file created for response-file was being cleaned up
before downstream steps could access it. Now using keep: true to
ensure the file persists until the job completes.

Also added script/ to eslint ignores for the mock server.

eslint.config.mjs

@@ -19,7 +19,7 @@ const compat = new FlatCompat({
 
 export default [
   {
-    ignores: ['**/coverage', '**/dist', '**/linter', '**/node_modules'],
+    ignores: ['**/coverage', '**/dist', '**/linter', '**/node_modules', 'script/**'],
   },
   ...compat.extends(
     'eslint:recommended',