fix: apply parse5-utils JSDoc->TS conversion and fix type mismatches

- Convert parse5-utils from JSDoc .js to TypeScript with parse5 v8 API
- Update parse5-utils package.json, tsconfig from fix/node24
- Fix polyfills-loader parse5 type imports for v8 compatibility

Assisted-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: bennypowers

package-lock.json

@@ -17,18 +17,17 @@
   "main": "dist/index.js",
   "exports": {
     ".": {
-      "types": "./index.d.ts",
-      "import": "./index.mjs",
-      "default": "./src/index.js"
+      "types": "./dist/index.d.ts",
+      "default": "./dist/index.js"
     }
   },
   "engines": {
     "node": ">=24.0.0"
   },
   "scripts": {
     "build": "tsc",
-    "test:node": "TS_NODE_COMPILER_OPTIONS='{\"module\":\"commonjs\",\"moduleResolution\":\"node\"}' mocha \"test/**/*.test.{ts,js,mjs,cjs}\" --require ts-node/register --reporter dot",
-    "test:watch": "TS_NODE_COMPILER_OPTIONS='{\"module\":\"commonjs\",\"moduleResolution\":\"node\"}' mocha \"test/**/*.test.{ts,js,mjs,cjs}\" --require ts-node/register --watch"
+    "test:node": "node --test 'test/**/*.test.mjs'",
+    "test:watch": "npm run test:node -- --watch"
   },
   "files": [
     "dist",