feat: add HTTP healthcheck endpoint via quarkus-smallrye-health

- pom.xml: add quarkus-smallrye-health dependency.
  Exposes /q/health/live and /q/health/ready endpoints (liveness
  and readiness probes for Quarkus apps).
- Dockerfile: install curl-minimal in the microdnf layer so the
  container has a real HTTP client. quarkus-micro-image is based
  on UBI 9 minimal and doesn't ship with curl by default.
- compose.yaml: healthcheck now hits GET /q/health/live with
  curl -f instead of the previous kill -0 1 (which only proved
  the process was alive, not that the HTTP server was responding).

The next CI run will rebuild the native binary with the health
extension baked in; old images pulled from :latest will keep
working since this is additive.

Dockerfile

@@ -2,7 +2,8 @@ FROM quay.io/quarkus/quarkus-micro-image:2.0
 WORKDIR /work/
 COPY build-output/shot-crafter-calculator-1.0.0-runner /work/application
 
-RUN chmod 775 /work /work/application \
+RUN microdnf install -y curl-minimal && microdnf clean all \
+  && chmod 775 /work /work/application \
   && chown -R 1001 /work \
   && echo "securerandom.source=file:/dev/urandom" >> /work/application