ci: load Pipeline definition from SCM

Jenkinsfile

@@ -0,0 +1,5 @@
+node {
+  stage('SCM Jenkinsfile') { checkout([$class: 'GitSCM', branches: [[name: '*/master']], userRemoteConfigs: [[url: 'http://service-6acce8de4873e494859dc96e:3000/codex-test/demo-ci-lab.git']], extensions: []]) }
+  try { stage('构建与测试') { sh 'sh ci/demo-build.sh'; junit 'reports/*.xml' } }
+  finally { stage('归档') { archiveArtifacts artifacts: 'artifacts/*', allowEmptyArchive: true } }
+}