Automate docker build on PRs (#647)

Jenkinsfile

@@ -43,6 +43,54 @@ pipeline {
           sh 'npx prettier --check .'
         }
       }
+      stage('Deploy docker image (PR)') {
+        when {
+          changeRequest()
+        }
+        steps {
+          script {
+            // If the PR comes from a fork, verify the fork owner is a linagora org member
+            if (env.CHANGE_FORK) {
+              def forkOwner = env.CHANGE_FORK
+              def memberStatus = sh(
+                script: """curl -s -o /dev/null -w "%{http_code}" \
+                  -H "Authorization: token \${GITHUB_CREDENTIAL_PSW}" \
+                  "https://api.github.com/orgs/linagora/members/${forkOwner}" """,
+                returnStdout: true
+              ).trim()
+              echo "GitHub org membership check returned HTTP ${memberStatus} for '${forkOwner}'"
+              if (memberStatus == '204') {
+                echo "Fork owner '${forkOwner}' is a linagora org member, proceeding."
+              } else if (memberStatus == '404') {
+                error("Fork owner '${forkOwner}' is not a member of the linagora organization. Skipping deploy.")
+              } else if (memberStatus == '401' || memberStatus == '403') {
+                error("Authentication/permission error validating fork owner: ${memberStatus}")
+              } else {
+                error("GitHub API error ${memberStatus} while checking membership for '${forkOwner}'")
+              }
+            }
+
+            def dockerTag = "pr-${env.CHANGE_ID}"
+            env.DOCKER_TAG = dockerTag
+            echo "Docker tag: ${dockerTag}"
+            sh 'npm run build'
+            sh 'docker build -t linagora/twake-calendar-web:$DOCKER_TAG .'
+            sh 'echo $DOCKER_HUB_CREDENTIAL_PSW | docker login -u $DOCKER_HUB_CREDENTIAL_USR --password-stdin'
+            sh 'docker push linagora/twake-calendar-web:$DOCKER_TAG'
+            sh """
+              HTTP_STATUS=\$(curl -s -o /tmp/gh_comment_response.json -w "%{http_code}" -X POST \\
+                -H "Authorization: token \${GITHUB_CREDENTIAL_PSW}" \\
+                -H "Content-Type: application/json" \\
+                -d "{\\"body\\": \\"Docker image published for this PR: linagora/twake-calendar-web:${dockerTag}\\"}" \\
+                "https://api.github.com/repos/linagora/twake-calendar-frontend/issues/\${CHANGE_ID}/comments")
+              if [ "\$HTTP_STATUS" -lt 200 ] || [ "\$HTTP_STATUS" -ge 300 ]; then
+                echo "WARNING: GitHub API comment failed with HTTP \$HTTP_STATUS"
+                cat /tmp/gh_comment_response.json
+              fi
+            """
+          }
+        }
+      }
       stage('Deploy docker images') {
         when {
           anyOf {