ops: add CI/CD pipeline, a/b rolling deploy, Gitea Actions workflow

- .gitea/workflows/deploy.yml — push-to-main triggers rolling deploy
- scripts/deploy-bluegreen.sh — a-stack then b-stack restart; Maven runs
  in Docker (no JDK needed on runner host); Caddy reload at end
- scripts/deploy-all.ps1 — emergency manual deploy from dev machine
- infra/docker-compose.yml — a/b pairs per service; wget health checks;
  Gitea service; Prometheus/Grafana/DB ports restricted to localhost
- infra/Caddyfile — dual upstreams with health-based routing
- infra/Dockerfile.* — one per service
- infra/prometheus.yml + grafana provisioning

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

infra/Dockerfile.demo

@@ -0,0 +1,8 @@
+FROM eclipse-temurin:21-jre-alpine
+RUN addgroup -S apix && adduser -S apix -G apix
+WORKDIR /app
+COPY apix-demo/target/quarkus-app/ quarkus-app/
+RUN chown -R apix:apix /app
+USER apix
+EXPOSE 8083
+ENTRYPOINT ["java", "-jar", "quarkus-app/quarkus-run.jar"]