ci(hermes-agent-image): run release boundary where git exists

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ci/Jenkinsfile.hermes-agent-image

@@ -139,6 +139,7 @@ spec:
     }
     stage('Enforce release boundary') {
       steps {
+        container('jnlp') {
         sh '''
           set -eu
           mkdir -p build
@@ -166,6 +167,7 @@ spec:
             "${HERMES_IMAGE}:git-${actual_revision}-build-${BUILD_NUMBER}" \
             > build/hermes-agent.destination
         '''
+        }
       }
     }
     stage('Reject replay before publish') {