feat: nb add env variable for sops

hosts/nb/users/dominik.nix

@@ -165,6 +165,7 @@ in
   programs.zsh = {
     shellInit = ''
       export OPENAI_API_KEY=$(cat ${config.sops.secrets.openai_api_key.path})
+      export SOPS_AGE_KEY_FILE="$HOME/.config/sops/age/key.age"
     '';
   };
 
@@ -175,6 +176,7 @@ in
     home.enableNixpkgsReleaseCheck = false;
     home.sessionVariables = {
       MOZ_ENABLE_WAYLAND = "1";
+      SOPS_AGE_KEY_FILE = "$HOME/.config/sops/age/key.age";
     };
 
     nixpkgs.config.allowUnfree = true;