ci: skip deploy-preview job for fork PRs (#13584)

Fork PRs don't have access to the Netlify and bot token secrets, so the
deploy step always failed and surfaced as a failing check on the PR.
Gate the job on the head repo matching the base repo so it's skipped
(not failed) for forks. Skipped checks don't block merge.

Author: ilhan007

.github/workflows/deploy-preview.yaml

@@ -33,8 +33,11 @@ permissions:
 
 jobs:
   deploy-preview:
+    # Skip for PRs from forks — they don't have access to the Netlify secrets,
+    # so the deploy step would always fail. A skipped check does not block merge.
+    if: github.event.pull_request.head.repo.full_name == github.repository
     runs-on: ubuntu-latest
-    
+
     steps:
     - name: Checkout
       uses: actions/checkout@v4