Fix ERR_REQUIRE_ESM: Use dynamic import for Lighthouse

lib/runner.js

@@ -1,4 +1,4 @@
-const lighthouse = require('lighthouse');
+// lighthouse is ESM only, imported dynamically
 const chromeLauncher = require('chrome-launcher');
 const fs = require('fs');
 const path = require('path');
@@ -11,6 +11,9 @@ const { v4: uuidv4 } = require('uuid');
  * @returns {Promise<object>} - Test results
  */
 async function runTest(url, options = {}) {
+  // Dynamically import Lighthouse (ESM)
+  const { default: lighthouse } = await import('lighthouse');
+
   const isMobile = options.isMobile ?? true; // Default to mobile
   const reportDir = path.join(__dirname, '..', 'reports');