scope PR CI workflow to only run on catalog changes

The PR validation workflow (Validate Contributor, Validate Contribution)
is only relevant when catalog content is modified. Adding a paths filter
prevents the workflow from running on unrelated PRs like dependabot
action version bumps.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: grokspawn

.github/workflows/build-verify-on-PR.yml

@@ -2,8 +2,10 @@ name: CI
 
 on:
   pull_request:
-    branches: 
+    branches:
     - '**'
+    paths:
+    - 'catalog/**'
 
 jobs:
   build: