Run CI on push to main so the badge stays current (#38)

The badge URL includes ?branch=main but CI only ran on pull_request,
so no run was ever recorded against main and the badge showed no status.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: dexwritescode

.github/workflows/ci.yaml

@@ -1,6 +1,8 @@
 name: CI
 
 on:
+  push:
+    branches: [ "main" ]
   pull_request:
     branches: [ "main" ]