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>

nginx/default.conf

@@ -0,0 +1,29 @@
+server {
+    listen       8080;
+    server_name  _;
+
+    root   /usr/share/nginx/html;
+    index  index.html;
+
+    charset utf-8;
+    charset_types text/css application/javascript application/json;
+
+    # 프록시(NPM) 뒤에 있으므로 실제 클라이언트 IP 로그
+    real_ip_header X-Forwarded-For;
+
+    gzip on;
+    gzip_min_length 1024;
+    gzip_types text/plain text/css application/javascript application/json image/svg+xml;
+
+    # 단일 정적 페이지 - 어떤 경로로 들어와도 index.html
+    location / {
+        try_files $uri $uri/ /index.html;
+        add_header Cache-Control "no-cache, must-revalidate";
+    }
+
+    location = /healthz {
+        access_log off;
+        default_type text/plain;
+        return 200 "ok\n";
+    }
+}