feat: deploy to Frostmoln production

The AWS deploy-prod job has failed since CI left AWS (no k8s.unbound.se
context on the runners). Deploys now go to the Frostmoln production
cluster (namespace schemas), the way the sites do.

Frostmoln enforces restricted Pod Security: the pod runs as the image's
non-root user with a matching securityContext. The prod-only manifests
move to the prod-frostmoln target; the ALB ingress becomes a Traefik one
with a Let's Encrypt certificate.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ma8eHhW59hLAJuLzBnLvUu

Dockerfile

@@ -12,7 +12,8 @@ RUN npm run postinstall && npm run generate && npm run lint && npm run test:cove
 FROM scratch as export
 COPY --from=builder /build/coverage /
 
-FROM amd64/nginx:1.31.7@sha256:227f31dac037a2f1cdbd17ca9eec940a76c6c1b3187f5285eca2c3edb5d19c31
+# Unprivileged (uid 101, port 8080): Frostmoln enforces restricted Pod Security.
+FROM nginxinc/nginx-unprivileged:1.31.6@sha256:1d26a516fb93b18f9c0214dc9c645054486e516f13ff09ef63d5bd5c622278a2
 MAINTAINER Joakim Olsson <joakim@unbound.se>
 
 COPY ./nginx/nginx.conf /etc/nginx/nginx.conf