Refactor Root layout theme and fonts. Encapsulate functions into separate files. Fix default theme handling when cookie is not set by fall-backing to the selected theme mode. (#103)

apps/web/lib/root-theme.ts

@@ -0,0 +1,16 @@
+import { cookies } from 'next/headers';
+
+type Theme = 'light' | 'dark' | 'system';
+
+/**
+ * @name getRootTheme
+ * @description Get the root theme from the cookies or default theme.
+ * @returns The root theme.
+ */
+export async function getRootTheme() {
+  const cookiesStore = await cookies();
+
+  const themeCookie = cookiesStore.get('theme')?.value as Theme
+
+  return themeCookie ?? process.env.NEXT_PUBLIC_DEFAULT_THEME_MODE ?? 'light';
+}