(chore) run staging dry-run on PRs to validate publication

Stage snapshot artifacts on PRs (with PR-{N}-SNAPSHOT version) to catch
Gradle publishing/POM issues before merge, matching the pcre4j pattern.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: alexey-pelykh

.github/workflows/ci.yaml

@@ -43,8 +43,10 @@ jobs:
           path: lib/build/outputs/aar/*-release.aar
 
       - name: Stage snapshot artifacts
-        if: ${{ github.event_name == 'push' && github.ref_name == 'main' }}
-        run: ./gradlew :lib:publishReleasePublicationToStagingDeployRepository -Puvccamera.version=main-SNAPSHOT
+        if: ${{ (github.event_name == 'push' && github.ref_name == 'main') || (github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == github.repository) }}
+        run: >
+          ./gradlew :lib:publishReleasePublicationToStagingDeployRepository
+          -Puvccamera.version=${{ github.event_name == 'pull_request' && format('PR-{0}-SNAPSHOT', github.event.pull_request.number) || 'main-SNAPSHOT' }}
 
       - name: Publish snapshot artifacts
         if: ${{ github.event_name == 'push' && github.ref_name == 'main' }}