feat: keep pi and nix features current

update-system.sh

@@ -21,10 +21,10 @@ trap cleanup EXIT
 
 git worktree add --detach "$work" "$baseline"
 cd "$work"
-# Only these stable release inputs advance. Neovim's source stays pinned.
-nix flake update nixpkgs home-manager
+# Advance package inputs to newest resolving branch heads. Neovim stays pinned.
+nix flake update nixpkgs home-manager nixpkgs-latest
 if git diff --quiet -- flake.lock; then
-  echo 'Stable inputs are already current.'
+  echo 'Package inputs are already current.'
   exit 0
 fi
 nix flake check --no-build --no-update-lock-file
@@ -32,7 +32,7 @@ nix build .#checks.x86_64-linux.updates .#checks.x86_64-linux.desktop-config \
   --no-update-lock-file --no-link
 git add flake.lock
 git -c user.name='NixOS Updater' -c user.email='nixos-updater@localhost' \
-  commit -m 'chore: update stable NixOS and Home Manager inputs'
+  commit -m 'chore: update NixOS package inputs'
 built=$(nix build .#nixosConfigurations.dev.config.system.build.toplevel \
   --no-update-lock-file --no-link --print-out-paths)
 candidate=$(git rev-parse HEAD)