feat(dns): PiHole answers an explicit LAN name list, not a zone wildcard

Public names are proxied CNAMEs to the Cloudflare Tunnel since PR #156 and
work from the LAN, so they should resolve publicly there too. Replace the
address=/${BASE_DOMAIN}/ wildcard with explicit entries: the LAN-only names
(derived from every controller:none HTTPRoute), gitea/nextcloud (off
Cloudflare's 100 MB / 100 s limits), keycloak/auth, and the L4 VIPs.

Add L0 check pihole-lan-names, mutation-tested. Correct docs that still
described public names as CNAME to wan. and the cloudflared entrypoint comment.

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

platform/pm-agent/README.md

@@ -72,11 +72,14 @@ Both are deliberate, and both fail **visibly** rather than silently:
    - **The nodes resolve the registry hostname to the WAN, so the TLS they fail to verify is
      the router's — DIAGNOSED 2026-10-06, and fixed in this change.** containerd pulls as a
      *node* process, so it resolves through the node's public upstreams
-     (`node_baseline_dns_servers` = the LAN gateway) rather than through Pi-hole. The public
-     answer for every name in this zone is a CNAME to `wan.home.keithjackson.dev` — the WAN
-     IP — which this router does not hairpin; it answers :443 with its own placeholder
+     (`node_baseline_dns_servers` = the LAN gateway) rather than through Pi-hole. At the time,
+     the public answer for every name in this zone was a CNAME to `wan.home.keithjackson.dev`
+     — the WAN IP — which this router does not hairpin; it answered :443 with its own placeholder
      certificate `CN=%D` carrying **no extensions, therefore no SANs**, which is precisely
-     `x509: certificate is not valid for any names`. The Gateway, the wildcard certificate
+     `x509: certificate is not valid for any names`. (Since 2026-11-08 the public answer is
+     Cloudflare's edge via the Tunnel, not the WAN IP — see `platform/externaldns/README.md`.
+     The pin is still the right path: it keeps registry pulls on the LAN and off Cloudflare's
+     proxy.) The Gateway, the wildcard certificate
      and the digest were never implicated. The fix is the pin this repository already uses
      for the Keycloak issuer, for the identical reason: `gitea.{{ k3s_base_domain }}` is now
      in `node_baseline_hosts_pins` — node configuration is Ansible's, declared in the