feat(nix): setup shell and env for nix

zsh/nix.zsh

@@ -0,0 +1,21 @@
+#
+# Nix interative setup
+#
+
+sort_nix_paths() {
+  local nix_paths=()
+
+  for p in "${(@)path}"; do
+    if [[ "$p" == "/nix/store/"* ]]; then
+      nix_paths+=("$p")
+    fi
+  done
+
+  for p in "${(@)nix_paths}"; do
+    path_prepend "$p"
+  done
+}
+
+if command-exists nix-shell; then
+  sort_nix_paths
+fi