Add Jenkinsfile for CI pipeline

Jenkinsfile

@@ -0,0 +1,48 @@
+pipeline {
+    agent any
+
+    tools {
+        nodejs 'NodeJS'
+    }
+
+    stages {
+        stage('Checkout') {
+            steps {
+                checkout scm
+            }
+        }
+
+        stage('Install Dependencies') {
+            steps {
+                dir('birthday_web_ui') {
+                    sh 'npm install'
+                }
+            }
+        }
+
+        stage('Lint') {
+            steps {
+                dir('birthday_web_ui') {
+                    sh 'npm run lint'
+                }
+            }
+        }
+
+        stage('Build') {
+            steps {
+                dir('birthday_web_ui') {
+                    sh 'npm run build'
+                }
+            }
+        }
+    }
+
+    post {
+        success {
+            echo 'Build successful!'
+        }
+        failure {
+            echo 'Build failed!'
+        }
+    }
+}