fix(dotfiles): qualify stable UID helpers

configs/nixos/AGENTS.md

@@ -40,6 +40,8 @@
 
 ## Gotchas
 
+- `configs/nixos/registry/stable-uid.nix` receives library functions through `lib`.
+  Qualify its library calls with `lib.`.
 - Guest modules are host-agnostic wiring, while host files own deployment-specific service configuration such as served volumes and host paths.
   For example, `guests/copyparty.nix` should expose options and translate them into guest mounts/service settings, while `hosts/pikachu/default.nix` chooses `/inbox`, `/media`, and their backing paths.
   Guest addresses and routes are host-level configuration because a guest module can be used on multiple hosts.