docs: add runbooks and Kubernetes Helm Chart

Add 6 runbook documents:
- 服务启动 (Service Startup)
- 服务停止 (Service Shutdown)
- 配置更新 (Configuration Update)
- 日志分析 (Log Analysis)
- 备份恢复 (Backup & Recovery)
- 安全事件 (Security Incident)

Add Kubernetes Helm Chart:
- Chart.yaml, values.yaml
- Deployment with health checks
- Ingress with TLS support
- PVC for data persistence
- PDB for high availability
- HPA for autoscaling
- ServiceAccount configuration

Add cron-backup.conf for automated backup scheduling.

kubernetes/user-management/Chart.yaml

@@ -0,0 +1,13 @@
+apiVersion: v2
+name: user-management
+description: A Helm chart for User Management System
+type: application
+version: 1.0.0
+appVersion: "1.0.0"
+keywords:
+  - user-management
+  - authentication
+  - rbac
+maintainers:
+  - name: DevOps Team
+    email: devops@example.com