Replace DNS-flip failover watcher with static vps.huskypup.net subdomains

The DNS-flip watcher (scripts/vps-dns-failover/) was designed but never
actually installed on the VPS despite being tracked as done - real gap,
found when asked whether the standby services are actually reachable.

New design: instead of dynamically flipping *.kube.huskypup.net between
home and VPS IPs, give the VPS site its own permanent, always-resolving
subdomain - vault/gitea/auth/n8n/nextcloud.vps.huskypup.net, each with
real Ingress+TLS on the VPS's own Traefik+cert-manager (both already
installed by Phase 0 bootstrap, just never wired up). No token-scoping
decision needed since there's no dynamic flipping - reuses the same
cert-manager token pattern as home.

Also scales Authentik/n8n/Nextcloud from 0 to 1 replica on the VPS so
the replicated data is actually browsable at all times, not just
present-but-unreachable. Their CNPG clusters are still read-only
replicas (spec.replica.enabled: true) - writes will error until a
deliberate manual promotion, but reads/browsing work now. Vault and
Gitea were already running continuously.

infrastructure/vps-standby/vault/manifests/ingress.yaml

@@ -0,0 +1,30 @@
+---
+# Public-ish access to the VPS Vault standby, replacing the old
+# "reachable over Netbird only" model with a stable, permanent hostname
+# (vault.vps.huskypup.net) that doesn't depend on home being up at all -
+# see the vps.huskypup.net subdomain design note in
+# infrastructure/vps-standby/cert-manager/manifests/cluster-issuer.yaml.
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: vps-vault
+  namespace: vault
+  annotations:
+    cert-manager.io/cluster-issuer: letsencrypt-production
+spec:
+  ingressClassName: traefik
+  tls:
+    - hosts:
+        - vault.vps.huskypup.net
+      secretName: vps-vault-tls
+  rules:
+    - host: vault.vps.huskypup.net
+      http:
+        paths:
+          - path: /
+            pathType: Prefix
+            backend:
+              service:
+                name: vps-vault-ui
+                port:
+                  number: 8200