feat(infra): production bootstrap — cert-manager, longhorn, monitoring

Add new bases for cert-manager (Let's Encrypt + wildcard cert), Longhorn
distributed storage, and monitoring (kube-prometheus-stack + Loki + Tempo
+ Grafana OIDC). Add cloud-init for Scaleway Elastic Metal provisioning.

Production overlay: add patches for postgres sizing, SeaweedFS volume,
OpenSearch storage, LiveKit service, Pingora host ports, resource limits,
and CNPG daily barman backups. Update cert-manager.yaml with full dnsNames
for all *.sunbeam.pt subdomains.

overlays/production/postgres-scheduled-backup.yaml

@@ -0,0 +1,12 @@
+apiVersion: postgresql.cnpg.io/v1
+kind: ScheduledBackup
+metadata:
+  name: postgres-daily
+  namespace: data
+spec:
+  # Daily at 02:00 UTC
+  schedule: "0 2 * * *"
+  backupOwnerReference: self
+  cluster:
+    name: postgres
+  method: barmanObjectStore