ci: optimize workflow triggers (#165)

- CI workflow now only runs on pull_request to main branch
- Added workflow_dispatch for manual triggering
- Removed push trigger to avoid duplicate runs (release handles push to main)
- Removed develop branch from triggers to simplify branch strategy

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <[email protected]>

Author: graycreate

.github/workflows/ci.yml

@@ -1,10 +1,9 @@
 name: CI
 
 on:
-  push:
-    branches: [ main, develop ]
   pull_request:
-    branches: [ main, develop ]
+    branches: [main]
+  workflow_dispatch:
 
 permissions:
   contents: read