fix: correct Node.js version references from 24 to 22 in comments and code

Fixed confusing messaging where comments mentioned Node 24 while actual requirement is Node 22:

- environment.ts: Fixed areWorkerThreadsAvailableSync() to check for >= 22 instead of >= 24
- workerUtils.ts: Updated comments to reference Node.js 22 LTS instead of 24
- embedding.ts: Updated ONNX threading comment to reference Node.js 22 LTS

Why Node 22 not Node 24:
- ONNX Runtime has stability issues in Node 24 (V8 HandleScope crashes)
- Node 22 LTS provides maximum stability with our embedding model
- These stale Node 24 references were causing user confusion

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/utils/workerUtils.ts

@@ -1,6 +1,6 @@
 /**
  * Utility functions for executing functions in Worker Threads (Node.js) or Web Workers (Browser)
- * This implementation leverages Node.js 24's improved Worker Threads API for better performance
+ * This implementation leverages Node.js 22's stable Worker Threads API for maximum reliability
  */
 
 import { isBrowser, isNode } from './environment.js'
@@ -82,7 +82,7 @@ export function executeInThread<T>(fnString: string, args: any): Promise<T> {
 
 /**
  * Execute a function in a Node.js Worker Thread
- * Optimized for Node.js 24 with improved Worker Threads performance
+ * Optimized for Node.js 22 LTS with stable Worker Threads performance
  */
 function executeInNodeWorker<T>(fnString: string, args: any): Promise<T> {
   return new Promise<T>((resolve, reject) => {