feat: use git-crypt for secret config that is ok to be in the nix store

.gitattributes

@@ -0,0 +1 @@
+secret-config.nix filter=git-crypt diff=git-crypt

nixos/server/default.nix

@@ -10,9 +10,6 @@
   ];
 
   kekleo.graphical = false;
-  kekleo.publicKeys = [
-    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOsLFjdS9JEcgBPa6NvOzpJp8coJPJwJFuM+PQCZ8brl leonhard"
-  ];
 
   users.users.leonhard = {
     initialPassword = "leonhard";

nixos/server/secrets/default.nix

@@ -3,6 +3,10 @@
   ...
 }:
 {
+  imports = [
+    ./secret-config.nix
+  ];
+
   sops.secrets.dyndns = {
     format = "dotenv";
     sopsFile = ./dyndns.env;