feat(cloudflared): Cloudflare Tunnel connector, Phase 1 (isolated, no traffic change)

Adds platform/cloudflared: a locally-managed tunnel whose ingress rules live in
git. LAN/VPN-only hosts (plex, plex-vip, jackett, pihole, pihole-dns, semaphore,
qbittorrent, radarr, sonarr, headlamp, unifi, crafty-mc) map to 404. The apex
and *.home go to cilium-gateway-shared.gateway over TLS with matchSNItoHost.
Last comes a catch-all 404. Nothing routes to the Kubernetes API.

- 2-replica Deployment, hard node spread, non-root, pinned digest, PDB
- default-deny plus an egress CNP: Cloudflare edge 7844/443, the Gateway, and
  Gateway backends by gateway-access=shared minus the LAN-only namespaces
  (needed because of the CVE-2025-30162 L7LB egress re-check)
- PodMonitor plus two alerts that fire on absent series, with promtool tests
- its own Flux Kustomization (dependsOn platform-config, wait:false, nothing
  depends on it), plus SOPS decryption patches in both overlays
- placeholder credentials (SOPS-encrypted) so it can merge before enrolment
- L0 cloudflared-ingress-rules, and a cloudflared_ scrape owner
- runbooks/cloudflare-tunnel.md and decisions/2026-11-08-cloudflare-tunnel.md

Co-Authored-By: Claude Opus 5.5 <[email protected]>

platform/cloudflared/podmonitor.yaml

@@ -0,0 +1,22 @@
+---
+# Scrapes cloudflared's own metrics server (:2000, `metrics:` in config.yaml) on every replica.
+# kube-prometheus-stack runs with podMonitorSelectorNilUsesHelmValues: false, so Prometheus selects
+# every PodMonitor in every namespace; the `release` label is kept for consistency with the
+# platform's other monitors. The ingress allow that lets this scrape through the namespace's
+# default-deny is cloudflared-allow-prometheus-scrape in networkpolicy.yaml.
+apiVersion: monitoring.coreos.com/v1
+kind: PodMonitor
+metadata:
+  name: cloudflared
+  namespace: cloudflared
+  labels:
+    app.kubernetes.io/name: cloudflared
+    release: kube-prometheus-stack
+spec:
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: cloudflared
+  podMetricsEndpoints:
+    - port: metrics
+      path: /metrics
+      interval: 30s