chore: Stop eagerly compiling stories in non-dev

Running the test suite triggers recompilation of storybook entries and slows down the test suite.

lib/medical_transcription_web/storybook.ex

@@ -9,5 +9,6 @@ defmodule MedicodeWeb.Storybook do
     # assets path are remote path, not local file-system paths
     css_path: "/assets/storybook.css",
     js_path: "/assets/storybook.js",
-    sandbox_class: "medical-transcription-web"
+    sandbox_class: "medical-transcription-web",
+    compilation_mode: :lazy
 end