Fix Windows native fallback test and speed badges

Author: Krablante

README.md

@@ -12,7 +12,8 @@
   <img alt="License MIT" src="https://img.shields.io/badge/license-MIT-555">
   <img alt="Node 20.19.4+" src="https://img.shields.io/badge/node-%3E%3D20.19.4-339933">
   <img alt="Codex compatible" src="https://img.shields.io/badge/codex-compatible-444">
-  <img alt="Cold scans 62 percent faster" src="https://img.shields.io/badge/cold%20scan-62%25%20faster-0f766e">
+  <img alt="Cold scan 96 percent plus faster" src="https://img.shields.io/badge/cold%20scan-96%25%2B%20faster-0f766e">
+  <img alt="Warm scan 99 percent plus faster" src="https://img.shields.io/badge/warm%20scan-99%25%2B%20faster-0f766e">
   <img alt="OpenAI pricing only" src="https://img.shields.io/badge/pricing-OpenAI%20only-111">
   <img alt="No database" src="https://img.shields.io/badge/database-none-0f766e">
 </p>

test/engine.test.mjs

@@ -529,10 +529,14 @@ for (let i = 0; i < 3000; i += 1) {
 }
 const fakeBin = path.join(root, 'fake-native-bin');
 await mkdir(fakeBin, { recursive: true });
-await writeFile(path.join(fakeBin, 'xargs'), '#!/bin/sh\nexit 1\n', { mode: 0o755 });
+if (process.platform === 'win32') {
+  await writeFile(path.join(fakeBin, 'xargs.cmd'), '@echo off\r\nexit /b 1\r\n');
+} else {
+  await writeFile(path.join(fakeBin, 'xargs'), '#!/bin/sh\nexit 1\n', { mode: 0o755 });
+}
 const previousPath = process.env.PATH;
 process.env.CDXUSAGE_SCAN_MODE = 'grep-batch';
-process.env.PATH = `${fakeBin}:${previousPath ?? ''}`;
+process.env.PATH = `${fakeBin}${path.delimiter}${previousPath ?? ''}`;
 try {
   const nativeEarlyExit = await collectUsage({
     codexHome: nativeEarlyExitHome,