Add in-tab display mode toggle for users

Let signed-in visitors override the OS color scheme from
the account menu without persisting across reloads, and
keep themed logos in sync with the effective mode.

Signed-off-by: Émile Ré <emile@probo.com>

apps/compliance-portal/src/main.tsx

@@ -21,6 +21,7 @@
 import { createRoot } from "react-dom/client";
 
 import "./index.css";
+import "#/lib/displayMode/displayMode";
 import "#/lib/i18n/i18n";
 
 import { App } from "./App";