tor-relay: wire beszel-agent with token secret and fix sops key

- Add hosts/tor-relay/host.nix import of host-token.nix so the agent
  gets its TOKEN from a sops-managed environment file
- Add secrets/tor-relay.yaml (encrypted beszel token for this host)
- Add creation_rules entry for secrets/tor-relay.yaml in .sops.yaml
- Update &lxc-tor-relay age key to the host's actual current key
  (old key was from a prior LXC incarnation; new key extracted from
  Switch-nix output: age1gl5ujmhd2pe37...)
- Re-encrypt secrets/common.yaml via sops updatekeys to swap in the
  new key, so the host can decrypt its password hash on next boot

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

hosts/tor-relay/host.nix

@@ -1,11 +1,22 @@
-_:
+{ ... }:
 
 {
+  imports = [
+    (import ../../modules/beszel/host-token.nix {
+      name = "tor-relay";
+      sopsFile = ../../secrets/tor-relay.yaml;
+    })
+  ];
+
   networking.hostName = "tor-relay";
 
   # No networking.hostId: only ZFS-touching hosts (server, docker) need one
   # for pool-import safety, and this host does neither.
 
+  services.beszel.agent.environment = {
+    KEY = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIFPR9kwtC4TAeTRu46A7+opZsYpxqkRJ+x/ZyB2GWCeG";
+  };
+
   # A genuinely new host (not a pre-refactor carry-over), so it tracks the
   # flake's current nixpkgs release rather than being pinned to an older one.
   system.stateVersion = "26.05";