update: system update & refactor

# Breaking Changes
- sops location movod to "system/dev/<dev-name>/sops/sops-conf.nix"
- flake devices declaration changes
- whole flake update

system/dev/dn-pre7780/services/netbird.nix

@@ -0,0 +1,11 @@
+{ config, ... }:
+{
+  imports = [
+    (import ../expr/netbird.nix {
+      domain = "pre7780.dn";
+      coturnPassFile = config.sops.secrets."netbird/coturn/password".path;
+      idpSecret = config.sops.secrets."netbird/oidc/secret".path;
+      dataStoreEncryptionKey = config.sops.secrets."netbird/dataStoreKey".path;
+    })
+  ];
+}