ci: use Jenkins harbor credential for image push auth

Jenkinsfile

@@ -93,21 +93,23 @@ spec:
     stage('Prep toolchain') {
       steps {
         container('builder') {
-          sh '''
-            set -euo pipefail
-            for attempt in 1 2 3 4 5; do
-              if apk add --no-cache bash git jq curl; then
-                break
-              fi
-              if [ "$attempt" -eq 5 ]; then
-                echo "apk add failed after ${attempt} attempts" >&2
-                exit 1
-              fi
-              sleep $((attempt * 2))
-            done
-            mkdir -p /root/.docker
-            cp /docker-config/config.json /root/.docker/config.json
-          '''
+          withCredentials([usernamePassword(credentialsId: 'harbor-robot', usernameVariable: 'HARBOR_USERNAME', passwordVariable: 'HARBOR_PASSWORD')]) {
+            sh '''
+              set -euo pipefail
+              for attempt in 1 2 3 4 5; do
+                if apk add --no-cache bash git jq curl; then
+                  break
+                fi
+                if [ "$attempt" -eq 5 ]; then
+                  echo "apk add failed after ${attempt} attempts" >&2
+                  exit 1
+                fi
+                sleep $((attempt * 2))
+              done
+              mkdir -p /root/.docker
+              printf '%s' "${HARBOR_PASSWORD}" | docker login registry.bstein.dev -u "${HARBOR_USERNAME}" --password-stdin
+            '''
+          }
         }
       }
     }