fix(build): use .#nixosConfiguration over .#nodes

In the build script this allows us to share a cache with the deploy script

flake.nix

@@ -270,7 +270,7 @@
                   || { echo "usage: build <HOST>..." >&2; exit 1; }
                 HOSTS=()
                 for h in "$@"; do
-                  HOSTS+=(".#nodes.$h.config.system.build.toplevel")
+                  HOSTS+=(".#nixosConfigurations.$h.config.system.build.toplevel")
                 done
                 nom build --no-link --print-out-paths --show-trace "''${HOSTS[@]}"
               '';