refactor(beszel): switch to universal token via secrets/common.yaml

Replace per-host host-token.nix imports with a single beszel-token secret
in secrets/common.yaml, wired once in enable-agent.nix. Host files now only
need services.beszel.agent.environment.KEY — no imports block required.

Delete modules/beszel/host-token.nix (no longer referenced anywhere).

Action needed: run `sops secrets/common.yaml` and add `beszel-token: <value>`
from the beszel hub UI before deploying.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hosts/ha-server-1/host.nix

@@ -1,12 +1,5 @@
 { vars, ... }:
 {
-  imports = [
-    (import ../../modules/beszel/host-token.nix {
-      name = "ha-server-1";
-      sopsFile = ../../secrets/ha-server-1.yaml;
-    })
-  ];
-
   networking = {
     hostName = vars.haServer1Host;
     hostId = "3a4b5c6d";
@@ -23,7 +16,7 @@
     nameservers = [ vars.domainControllerIp ];
   };
 
-  # Set KEY after pairing this host with the beszel hub; the token is sops-managed.
+  # Set KEY after pairing this host with the beszel hub (see docs/beszel.md).
   # services.beszel.agent.environment.KEY = "";
 
   system.stateVersion = "26.05";

hosts/ha-server-2/host.nix

@@ -1,12 +1,5 @@
 { vars, ... }:
 {
-  imports = [
-    (import ../../modules/beszel/host-token.nix {
-      name = "ha-server-2";
-      sopsFile = ../../secrets/ha-server-2.yaml;
-    })
-  ];
-
   networking = {
     hostName = vars.haServer2Host;
     hostId = "7e8f9a0b";
@@ -23,7 +16,7 @@
     nameservers = [ vars.domainControllerIp ];
   };
 
-  # Set KEY after pairing this host with the beszel hub; the token is sops-managed.
+  # Set KEY after pairing this host with the beszel hub (see docs/beszel.md).
   # services.beszel.agent.environment.KEY = "";
 
   system.stateVersion = "26.05";

hosts/nix-cache/host.nix

@@ -1,13 +1,6 @@
 { vars, ... }:
 
 {
-  imports = [
-    (import ../../modules/beszel/host-token.nix {
-      name = "nix-cache";
-      sopsFile = ../../secrets/nix-cache.yaml;
-    })
-  ];
-
   networking = {
     hostName = vars.nixCacheHost;
     useDHCP = false;

hosts/server/host.nix

@@ -1,13 +1,6 @@
 { vars, ... }:
 
 {
-  imports = [
-    (import ../../modules/beszel/host-token.nix {
-      name = "server";
-      sopsFile = ../../secrets/server.yaml;
-    })
-  ];
-
   networking = {
     hostName = vars.nfsServerHost;
     hostId = "6689f93e";

hosts/tailscale-router/host.nix

@@ -1,13 +1,6 @@
 { vars, ... }:
 
 {
-  imports = [
-    (import ../../modules/beszel/host-token.nix {
-      name = "tailscale-router";
-      sopsFile = ../../secrets/tailscale-router.yaml;
-    })
-  ];
-
   networking = {
     hostName = "tailscale-router";
     useDHCP = false;

hosts/tor-relay/host.nix

@@ -1,13 +1,6 @@
 { vars, ... }:
 
 {
-  imports = [
-    (import ../../modules/beszel/host-token.nix {
-      name = "tor-relay";
-      sopsFile = ../../secrets/tor-relay.yaml;
-    })
-  ];
-
   networking = {
     hostName = "tor-relay";
     useDHCP = false;