nix-cache: switch DNS to nix-cache02

- Move nix-cache CNAME from nix-cache01 to nix-cache02
- Remove actions1 CNAME (service removed)
- Update proxy.nix to serve canonical domain on nix-cache02
- Promote nix-cache02 to prod tier with build-host role

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

hosts/nix-cache01/configuration.nix

@@ -11,8 +11,6 @@
     ../../common/vm
   ];
 
-  homelab.dns.cnames = [ "nix-cache" "actions1" ];
-
   homelab.host.role = "build-host";
 
   fileSystems."/nix" = {

hosts/nix-cache02/configuration.nix

@@ -13,11 +13,13 @@
     ../../common/vm
   ];
 
-  # Host metadata (adjust as needed)
   homelab.host = {
-    tier = "test";  # Start in test tier, move to prod after validation
+    tier = "prod";
+    role = "build-host";
   };
 
+  homelab.dns.cnames = [ "nix-cache" ];
+
   # Enable Vault integration
   vault.enable = true;
 

services/nix-cache/proxy.nix

@@ -1,10 +1,10 @@
 { pkgs, config, ... }:
 let
-  # nix-cache01 serves the canonical nix-cache.home.2rjus.net
-  # nix-cache02 serves nix-cache02.home.2rjus.net (for testing before DNS cutover)
+  # nix-cache02 serves the canonical nix-cache.home.2rjus.net
+  # nix-cache01 serves nix-cache01.home.2rjus.net (deprecated, pending decommission)
   hostname = config.networking.hostName;
   domain =
-    if hostname == "nix-cache01" then
+    if hostname == "nix-cache02" then
       "nix-cache.home.2rjus.net"
     else
       "${hostname}.home.2rjus.net";