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]>

runbooks/README.md

@@ -123,6 +123,9 @@ Each affected runbook says so on its own page and gives the by-hand equivalent.
 - **`vpn-remote-access`** — the INBOUND remote-access VPN (WireGuard, udp/51820): standing it up,
   enrolling and revoking devices, and the off-LAN checks that are the only honest proof it works.
   The opposite direction to the two pages above — do not confuse them.
+- **`cloudflare-tunnel`** — the Cloudflare Tunnel connector (inbound HTTPS from the Cloudflare edge to
+  the shared Gateway): enrolling it, the canary, `CloudflaredTunnelDown` / `CloudflaredReplicasDegraded`,
+  and rollback. Never `cloudflared tunnel route dns` — external-dns owns the records.
 
 ### Backups and DR
 - **`backup-failure`** — a Velero backup failed. The R2 object-tagging incompatibility is documented here.