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-server/services/default.nix

@@ -0,0 +1,11 @@
+{
+  imports = [
+    ./actual-budget.nix
+    ./bitwarden.nix
+    ./docmost.nix
+    ./mail-server.nix
+    ./nextcloud.nix
+    ./paperless-ngx.nix
+    ./metrics.nix
+  ];
+}