refactor: reorganize server modules

- Moved each individual service definition into a dedicated `services/`
  directory under every server module (e.g.
`modules/servers/bragi/services/`).
- Updated the corresponding `default.nix` files to import the renamed
  service modules from the new location.
- Applied the same changes across all server modules, ensuring
  the API and import paths remain consistent.

helpers.nix

@@ -19,7 +19,7 @@
   serverExtras =
     if host.type == "server"
     then [
-      ./modules/servers/general
+      # ./modules/servers/general
       ./modules/servers/${name}
       ./modules/servers/home-manager
     ]