ci: add workflow_dispatch trigger to CI workflow (#8)

Enables manual CI runs for release-please PRs that don't
automatically trigger CI (only modify CHANGELOG.md).

Co-authored-by: Gabe@w7dev <gabor@w7-7.net>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: 3 people

.github/workflows/ci.yml

@@ -5,6 +5,7 @@ on:
     branches: [main, dev]
   pull_request:
     branches: [main, dev]
+  workflow_dispatch:  # Allow manual trigger for release-please PRs
 
 # Cancel in-progress runs on same branch
 concurrency: