feat(tazjin/nixos): set up yggdrasil on all physical machines

Change-Id: I1d722c6d2e6192c445e77cb9b186a5320c2a60ec
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12485
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

users/tazjin/nixos/koptevo/default.nix

@@ -218,6 +218,10 @@ in
         Listen = true;
         Port = 9443; # yggd
       }];
+
+      AllowedPublicKeys = [
+        "573fd89392e2741ead4edd85034c91c88f1e560d991bbdbf1fccb6233db4d325" # koptevo
+      ];
     };
   };