Stop losing tsnet state on redeploys

flake.nix

@@ -87,6 +87,7 @@
             serviceConfig = {
               DynamicUser = true;
               RuntimeDirectory = name;
+              StateDirectory = name;
               ExecStartPre = "!${pkgs.writeShellScript "get-authkey" ''
                 set -e
                 TS_API_CLIENT_ID=${cfg.clientId} TS_API_CLIENT_SECRET=$(cat ${cfg.clientSecretFile}) ${self.packages.${pkgs.system}.get-authkey}/bin/get-authkey -ephemeral -tags ${lib.concatStringsSep "," cfg.tags} > $RUNTIME_DIRECTORY/authkey