commerce-ingress: redirect root to /app instead of 404ing

commerce.cruzcloud.net (medusa-svc) has no route at "/" — Medusa only
serves /health, /app (admin), /store, etc. lab-agent's generic public
domain check flagged the resulting 404 as an anomaly every cycle even
though the service is healthy.

Adds a Traefik Middleware (redirectRegex) scoped to the commerce host
that 301s "/" to "/app", so the DNS/routing layer owns the entry point
instead of every client (including monitoring) having to know to
append /app manually. Regex includes the host explicitly because the
same Ingress also routes media.cruzcloud.net and shares
router.middlewares at the Ingress-annotation level.

workloads/ecommerce/commerce/kustomization.yaml

@@ -9,3 +9,4 @@ resources:
   - minio-bootstrap-job.yaml
   - medusa/
   - ingress-commerce.yaml
+  - middleware-commerce-redirect.yaml