fix(ci): use verified Jenkins SSH key path for deploy stage

Jenkinsfile

@@ -85,18 +85,15 @@ pipeline {
 
 stage('Deploy') {
   steps {
-    withCredentials([sshUserPrivateKey(
-      credentialsId: "${env.DEPLOY_SSH_CREDENTIAL_ID}",
-      keyFileVariable: 'SSH_KEY',
-      usernameVariable: 'SSH_USER'
-    )]) {
     sh '''
 bash <<EOF
 set -euxo pipefail
 
+SSH_KEY="/var/lib/jenkins/.ssh/plesk_agency_deploy"
+SSH_USER="deploy"
 SSH_OPTS="-i ${SSH_KEY} -o BatchMode=yes -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null"
 
-echo "SSH user from credential: ${SSH_USER}"
+echo "SSH user from configured deploy key: ${SSH_USER}"
 echo "SSH key file path: ${SSH_KEY}"
 ls -l "${SSH_KEY}"
 ssh-keygen -y -f "${SSH_KEY}"
@@ -150,7 +147,6 @@ ssh ${SSH_OPTS} "$SSH_USER@$APP_HOST" "docker inspect plesk-agency-portal --form
 EOF
     '''
   }
-  }
 }
 
     stage('Smoke check') {