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

k8s/base/ingress.yaml

@@ -0,0 +1,30 @@
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: dyn-ddns
+  annotations:
+    # Traefik
+    traefik.ingress.kubernetes.io/router.entrypoints: websecure
+    traefik.ingress.kubernetes.io/router.tls: "true"
+    cert-manager.io/cluster-issuer: "letsencrypt-prod"
+    
+    # NGINX (uncomment if using NGINX ingress)
+    # kubernetes.io/ingress.class: nginx
+    # cert-manager.io/cluster-issuer: "letsencrypt-prod"
+    # nginx.ingress.kubernetes.io/ssl-redirect: "true"
+spec:
+  tls:
+  - hosts:
+    - dyn.dws.rip
+    secretName: dyn-ddns-tls
+  rules:
+  - host: dyn.dws.rip
+    http:
+      paths:
+      - path: /
+        pathType: Prefix
+        backend:
+          service:
+            name: dyn-ddns
+            port:
+              number: 80