Add Kubernetes/K3s deployment manifests and documentation

- Complete k8s manifests with Kustomize support
- Production and staging overlays
- ConfigMap/Secret management
- Ingress with TLS (Traefik/NGINX)
- Persistent storage for SQLite
- Comprehensive k8s README with operations guide
- Updated main README with k8s deployment instructions
- Gitignore for k8s secrets

Usage:
  kubectl apply -k k8s/overlays/production

README.md

@@ -77,9 +77,11 @@ TRUSTED_PROXIES=10.0.0.0/8,172.16.0.0/12
 
 ### Deployment
 
+#### Docker Compose (Recommended for single node)
+
 ```bash
 # Clone and start
-git clone <repo>
+git clone https://git.dws.rip/DWS/dyn.git
 cd dyn
 docker-compose up -d
 
@@ -90,6 +92,44 @@ docker-compose logs -f
 docker-compose down
 ```
 
+#### Kubernetes / K3s
+
+For production deployments on Kubernetes or K3s clusters:
+
+```bash
+# Clone repository
+git clone https://git.dws.rip/DWS/dyn.git
+cd dyn
+
+# Create your secrets file
+cp k8s/overlays/production/secrets.example.yaml k8s/overlays/production/secrets.yaml
+# Edit secrets.yaml with your actual Technitium credentials
+
+# Deploy with kustomize
+kubectl apply -k k8s/overlays/production
+
+# Or with kubectl 1.14+ (built-in kustomize)
+kubectl apply -k k8s/overlays/production
+
+# Check deployment status
+kubectl get pods -n dyn-ddns
+kubectl logs -n dyn-ddns -l app=dyn-ddns
+
+# Delete deployment
+kubectl delete -k k8s/overlays/production
+```
+
+**Kustomize Overlays:**
+- `k8s/overlays/production` - Production setup (2 replicas, higher resource limits)
+- `k8s/overlays/staging` - Staging environment (1 replica, relaxed rate limits)
+
+**Requirements:**
+- Cert-manager (for TLS certificates via Let's Encrypt)
+- Traefik or NGINX ingress controller
+- Persistent storage class (for SQLite database)
+
+See [k8s/README.md](k8s/README.md) for detailed Kubernetes deployment documentation.
+
 ## API Endpoints
 
 ### Web UI