Fix missing access import in scriptDownloader.js

- Add missing 'access' import from 'fs/promises'
- This was causing checkScriptExists method to fail with 'access is not defined' error
- Now properly detects when script files exist locally
- Fixes issue where UI shows 'Load Script' instead of 'Install' button for downloaded scripts

src/server/services/scriptDownloader.js

@@ -1,6 +1,6 @@
 // Real JavaScript implementation for script downloading
 import { join } from 'path';
-import { writeFile, mkdir } from 'fs/promises';
+import { writeFile, mkdir, access } from 'fs/promises';
 
 export class ScriptDownloaderService {
   constructor() {