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/cert-manager/manifests/cluster-issuer.yaml

@@ -0,0 +1,28 @@
+---
+# cert-manager itself is installed directly by scripts/vps-bootstrap.sh
+# (Phase 0, out-of-band like k3s/Netbird) - not GitOps-managed here. This
+# ClusterIssuer just rides the same GitOps pipeline as everything else in
+# vps-standby, DNS-01 via Cloudflare (same pattern as home's
+# infrastructure/cert-manager/manifests/letsencrypt-issuer.yaml).
+#
+# cloudflare-token-secret is a plain Secret copied here manually
+# (kubectl, not git - same reasoning as every other VPS secret):
+#   kubectl -n cert-manager create secret generic cloudflare-token-secret \
+#     --from-literal=cloudflare-token=<same token as home's cert-manager>
+apiVersion: cert-manager.io/v1
+kind: ClusterIssuer
+metadata:
+  name: letsencrypt-production
+spec:
+  acme:
+    server: https://acme-v02.api.letsencrypt.org/directory
+    email: garrettstone499@gmail.com
+    privateKeySecretRef:
+      name: letsencrypt-production
+    solvers:
+      - dns01:
+          cloudflare:
+            email: garrettstone499@gmail.com
+            apiTokenSecretRef:
+              name: cloudflare-token-secret
+              key: cloudflare-token