fix mix usage for prod

lib/aprsme_web/live/locale_hook.ex

@@ -3,6 +3,7 @@ defmodule AprsmeWeb.LocaleHook do
   LiveView hook for setting locale based on Accept-Language header.
   This ensures that LiveView updates maintain the correct locale.
   """
+  import Config, only: [config_env: 0]
   import Phoenix.Component
 
   # Cache supported locales at compile time
@@ -11,7 +12,7 @@ defmodule AprsmeWeb.LocaleHook do
   def on_mount(:set_locale, params, session, socket) do
     # Only set locale in production to allow seeing "xx" placeholders in dev
     locale =
-      if Mix.env() == :prod do
+      if config_env() == :prod do
         get_locale_from_session(session) || "en"
       end