Add static crossword site with nginx image and k8s manifests

- site/index.html: Russian literature crossword page
- Dockerfile + nginx conf serving on 8080 with /healthz
- k8s Deployment + NodePort Service (31380) in plpark-int-ns
- Jenkinsfile: build/push to gitea registry, apply to rancher

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,8 @@
+FROM nginx:1.27-alpine
+
+# 기본 서버 설정 제거 후 8080 포트용 설정 적용
+RUN rm -f /etc/nginx/conf.d/default.conf
+COPY nginx/default.conf /etc/nginx/conf.d/default.conf
+COPY site/ /usr/share/nginx/html/
+
+EXPOSE 8080