chore: add test server deployment workflow for port 8081

Author: huggywuggy1289

.github/workflows/deploy-test.yml

@@ -0,0 +1,57 @@
+name: Java CI/CD - Test Server (Port 8081)
+
+on:
+  push:
+    branches: [ "feature/apple-login-split" ] # 이 브랜치에 푸시할 때만 작동
+
+jobs:
+  build-and-deploy:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
+
+      - name: Build with Gradle
+        run: ./gradlew clean build -x test
+
+      # 1. 빌드된 JAR 파일을 EC2로 전송
+      - name: Copy JAR to EC2
+        uses: appleboy/scp-action@v0.1.7
+        with:
+          host: ${{ secrets.EC2_HOST }}
+          username: ${{ secrets.EC2_USER }}
+          key: ${{ secrets.EC2_SSH_KEY }}
+          source: "build/libs/NITROGEN-0.0.1-SNAPSHOT.jar"
+          target: "~/app/Nitrogen_Server/build/libs"
+          strip_components: 2
+
+      # 2. 서버에 접속해서 8081 서버만 교체
+      - name: Execute Remote SSH Commands
+        uses: appleboy/ssh-action@v1.0.3
+        with:
+          host: ${{ secrets.EC2_HOST }}
+          username: ${{ secrets.EC2_USER }}
+          key: ${{ secrets.EC2_SSH_KEY }}
+          script: |
+            cd ~/app/Nitrogen_Server/build/libs
+
+            # 8081 포트를 사용 중인 프로세스만 종료 (운영 서버 8080은 유지)
+            sudo fuser -k 8081/tcp || true
+            
+            # 불필요한 파일 삭제
+            find . -name "*-plain.jar" -delete
+            
+            # 테스트 서버 실행 (포트 8081, 테스트용 yml 사용, 로그 파일 분리)
+            nohup java -jar NITROGEN-0.0.1-SNAPSHOT.jar \
+            --spring.config.location=file:./application-test.yml \
+            --server.port=8081 \
+            > nohup_dev.out 2>&1 &