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/overlays/production/deployment-patch.yaml

@@ -0,0 +1,16 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: dyn-ddns
+spec:
+  template:
+    spec:
+      containers:
+      - name: dyn-ddns
+        resources:
+          requests:
+            memory: "128Mi"
+            cpu: "200m"
+          limits:
+            memory: "512Mi"
+            cpu: "1000m"

k8s/overlays/production/kustomization.yaml

@@ -0,0 +1,28 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - namespace.yaml
+  - ../../base
+  - secrets.yaml
+
+namePrefix: prod-
+namespace: dyn-ddns
+
+commonLabels:
+  environment: production
+
+configMapGenerator:
+  - name: dyn-ddns-config
+    behavior: merge
+    literals:
+      - TECHNITIUM_URL=https://dns.dws.rip
+      - RATE_LIMIT_PER_IP=10
+      - RATE_LIMIT_PER_TOKEN=1
+
+patchesStrategicMerge:
+  - deployment-patch.yaml
+
+replicas:
+  - name: dyn-ddns
+    count: 2

k8s/overlays/production/namespace.yaml

@@ -0,0 +1,7 @@
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: dyn-ddns
+  labels:
+    app.kubernetes.io/name: dyn-ddns
+    app.kubernetes.io/part-of: dws-dns

k8s/overlays/production/secrets.example.yaml

@@ -0,0 +1,12 @@
+apiVersion: v1
+kind: Secret
+metadata:
+  name: dyn-ddns-secrets
+type: Opaque
+stringData:
+  # Replace with your actual Technitium API token
+  TECHNITIUM_TOKEN: "your-production-api-token-here"
+  
+  # Or use username/password (not recommended for production)
+  # TECHNITIUM_USERNAME: "admin"
+  # TECHNITIUM_PASSWORD: "your-password"

k8s/overlays/staging/deployment-patch.yaml

@@ -0,0 +1,17 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: dyn-ddns
+spec:
+  replicas: 1
+  template:
+    spec:
+      containers:
+      - name: dyn-ddns
+        resources:
+          requests:
+            memory: "64Mi"
+            cpu: "100m"
+          limits:
+            memory: "256Mi"
+            cpu: "500m"

k8s/overlays/staging/kustomization.yaml

@@ -0,0 +1,24 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - namespace.yaml
+  - ../../base
+  - secrets.yaml
+
+namePrefix: staging-
+namespace: dyn-ddns-staging
+
+commonLabels:
+  environment: staging
+
+configMapGenerator:
+  - name: dyn-ddns-config
+    behavior: merge
+    literals:
+      - TECHNITIUM_URL=https://dns-staging.dws.rip
+      - RATE_LIMIT_PER_IP=100
+      - RATE_LIMIT_PER_TOKEN=10
+
+patchesStrategicMerge:
+  - deployment-patch.yaml

k8s/overlays/staging/namespace.yaml

@@ -0,0 +1,7 @@
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: dyn-ddns-staging
+  labels:
+    app.kubernetes.io/name: dyn-ddns
+    app.kubernetes.io/part-of: dws-dns

k8s/overlays/staging/secrets.example.yaml

@@ -0,0 +1,8 @@
+apiVersion: v1
+kind: Secret
+metadata:
+  name: dyn-ddns-secrets
+type: Opaque
+stringData:
+  # Replace with your staging Technitium credentials
+  TECHNITIUM_TOKEN: "your-staging-api-token-here"