debug: add trace logs to onParse and webhook handler

apps/backend/src/routes/line.ts

@@ -4,6 +4,9 @@ import { lineConfig, lineClient } from '../lib/lineClient';
 import crypto from 'crypto';
 
 const webhookHandler = async ({ request, body, set }: { request: Request, body: any, set: any }) => {
+  console.log('[LINE Webhook] Handler body type:', typeof body);
+  console.log('[LINE Webhook] Channel Secret configured:', !!lineConfig.channelSecret, lineConfig.channelSecret ? lineConfig.channelSecret.substring(0, 4) + '...' : 'NONE');
+
   // 1. Verify Signature
   const signature = request.headers.get('x-line-signature');
   if (!signature) {