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

.gitignore

@@ -50,4 +50,9 @@ Thumbs.db
 
 # Temporary files
 *.tmp
-*.temp
+*.temp
+
+# Melange / apko build artifacts
+packages/
+melange.rsa
+melange.rsa.pub