feat: deploy to Frostmoln production (#391)

Moves the production deploy from AWS to the Frostmoln production cluster (namespace `schemas`), with unboundsoftware/schemas.

- `deploy-prod` (AWS, failing since CI left AWS) → `deploy-prod-frostmoln`: `deploy prod-frostmoln -n schemas`.
- Restricted Pod Security: `nginxinc/nginx-unprivileged` (uid 101, port 8080; 1.31.7 isn't published for it yet, so 1.31.6). `nginx.conf`: no `user`, pid and temp paths under `/tmp`, `listen 8080`. Configs copied with `--chmod=644`. Service is ClusterIP.
- `autoscale-prod`/`pdb-prod` → `-prod-frostmoln`; the ALB ingress → a Traefik one for `/` on `schemas.unbound.se` (the API's `/query` ingress wins on the longer path).

Checked locally (amd64): as uid 101 with all capabilities dropped, `/health`, `/` and SPA routes 200, security headers present.

**Merge with** the schemas PR, after infra#1878 is applied.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

https://claude.ai/code/session_01Ma8eHhW59hLAJuLzBnLvUu
Reviewed-on: #391

k8s/autoscale-prod.yaml

@@ -1,18 +0,0 @@
-apiVersion: autoscaling/v2
-kind: HorizontalPodAutoscaler
-metadata:
-  name: schemas-app
-spec:
-  scaleTargetRef:
-    apiVersion: apps/v1
-    kind: Deployment
-    name: schemas-app
-  minReplicas: 2
-  maxReplicas: 10
-  metrics:
-  - type: Resource
-    resource:
-      name: cpu
-      target:
-        type: Utilization
-        averageUtilization: 80