stem95su: release the public CNAME (dns_type=none) for the Pages cutover

First half of the ADR-0018 stem95su cutover: the tunnel-target CNAME is
destroyed so stacks/valia-sites can create the Pages-target record for
the same name (Cloudflare allows one CNAME per name; the follow-up
commit flips manage_dns=true there). stem_video.mp4 was compressed to
21.4MB with Viktor's explicit OK, clearing the 25MB Pages cap; content
is already deployed on the stem95su Pages project. Brief public
NXDOMAIN window between the two applies is accepted.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

stacks/stem95su/main.tf

@@ -168,6 +168,9 @@ module "ingress" {
   service_name    = kubernetes_service.stem95su.metadata[0].name
   port            = "80"
   host            = "stem95su"
-  dns_type        = "proxied"
+  # DNS moved to stacks/valia-sites (ADR-0018 cutover): the public CNAME now
+  # points at Cloudflare Pages, not the tunnel. Ingress kept only until the
+  # serving stack is retired.
+  dns_type        = "none"
   tls_secret_name = var.tls_secret_name
 }