Change release-insiders workflow to manual trigger only

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: Boshen

.github/workflows/release-insiders.yml

@@ -1,8 +1,7 @@
 name: Release Insiders
 
 on:
-  push:
-    branches: [main]
+  workflow_dispatch:
 
 permissions:
   contents: read