ci: add workflow_dispatch trigger to release workflow

Allows manual triggering of the release workflow for testing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/release.yml

@@ -3,6 +3,7 @@ name: Release
 on:
   push:
     branches: [main]
+  workflow_dispatch:
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}