Fix identified issues with server consolidation

inventory-server/chat/routes.js

@@ -1,5 +1,12 @@
-const express = require('express');
-const path = require('path');
+import express from 'express';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+// ESM polyfill — Phase 9 §9.1. Handlers below use __dirname to resolve the
+// db-convert/db/files/{uploads,avatars} static asset paths.
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const router = express.Router();
 
 // Serve uploaded files with proper mapping from database paths to actual file locations
@@ -646,4 +653,4 @@ router.get('/users/:userId/search', async (req, res) => {
   }
 });
 
-module.exports = router; 
+export default router;