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

Dockerfile

@@ -1,4 +1,6 @@
 # syntax=docker/dockerfile:1.6
+# NOTE: The primary build method is now melange + apko (see melange.yaml / apko.yaml).
+# This Dockerfile is kept for local dev and Docker Compose backward compatibility.
 FROM python:3.12.7-slim AS builder
 
 ENV PYTHONDONTWRITEBYTECODE=1 \