Add melange/apko build pipeline and Kubernetes manifests

- Add melange.yaml for distroless package build
- Add apko.yaml for minimal container image
- Add GitHub Actions workflow for melange/apko CI build
- Add Kubernetes manifests (deployment, service, configmap, secret, redis)
- Update Dockerfile, .gitignore, and docker-compose.yml

k8s/service.yaml

@@ -0,0 +1,17 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: apcupsd-client
+  namespace: apcupsd
+  labels:
+    app.kubernetes.io/name: apcupsd-client
+    app.kubernetes.io/part-of: apcupsd-client
+spec:
+  type: LoadBalancer
+  selector:
+    app.kubernetes.io/name: apcupsd-client
+  ports:
+    - name: http
+      protocol: TCP
+      port: 10280
+      targetPort: 8000