Remove k8s-server host

Drop k8s-server from flake, Makefile targets, modules
(kubernetes.nix, docker-registry.nix), install script and
hardware config. Remove related registry vhost, port 6443
and NAT rules from gateway.nix. Drop K8s-Server section
and dangling markdown wrapper from README.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

modules/gateway.nix

@@ -42,20 +42,6 @@
           reverse_proxy 10.202.82.6:3000
         '';
       };
-      "registry.home.lindenfelser.de" = {
-        extraConfig = ''
-          @registry host registry.home.lindenfelser.de
-          basicauth @registry {
-            admin $2a$14$Ga5BCiHvtlfRjdnlI9bhseFnNZ8dwXsLz4t1FdSemA1mAUV/vA1oi
-          }
-          reverse_proxy @registry https://10.202.82.7:5000 {
-            transport http {
-              tls
-              tls_insecure_skip_verify
-            }
-          }
-        '';
-      };
     };
   };
 
@@ -69,7 +55,6 @@
     80    # HTTP (Caddy)
     443   # HTTPS (Caddy)
     2222  # External SSH to Gitea
-    6443  # Kubernetes API to k8s-server
   ];
 
   networking.firewall.allowedUDPPorts = [
@@ -85,7 +70,6 @@
     # Hairpin NAT for LAN clients hitting gateway:2222 so replies go back via gateway
     extraCommands = ''
       iptables -t nat -A POSTROUTING -p tcp -d 10.202.82.6 --dport 2222 -j MASQUERADE
-      iptables -t nat -A POSTROUTING -p tcp -d 10.202.82.7 --dport 6443 -j MASQUERADE
     '';
     forwardPorts = [
       {
@@ -93,11 +77,6 @@
         sourcePort = 2222;
         destination = "10.202.82.6:2222";
       }
-      {
-        proto = "tcp";
-        sourcePort = 6443;
-        destination = "10.202.82.7:6443";
-      }
     ];
   };
 }