Add impermanence-safety to tsnet-proxy state directories

Fixes reboots creating `-2` names

flake.nix

@@ -66,6 +66,7 @@
           }));
         };
       };
+      config.bluepython508.impermanence.local.directories = lib.mapAttrsToList (key: _: "/var/lib/tsnet-proxy-${key}");
       config.systemd.services = let
         cfg = config.services.bluepython508.tsnet-proxy;
       in