ci: run vulnerability triage on every push to main

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: brendan-kellam

.github/workflows/vulnerability-triage.yml

@@ -1,6 +1,9 @@
 name: Vulnerability Scan & Triage
 
 on:
+  push:
+    branches:
+      - main
   schedule:
     # Run daily at 6am Pacific (13:00 UTC during PDT)
     - cron: '0 13 * * *'