feat: remove dark mode toggle, switch to prefers-color-scheme

This means it's not possible to manually change the theme, but all major operating systems
support global dark mode now, so it shouldn't be a huge problem.
Will re-add the dark mode toggle if the Sec-CH-Prefers-Color-Scheme header gets added to Firefox and Safari.

Foxnouns.Frontend/app/routes/auth.log-in/route.tsx

@@ -21,7 +21,7 @@ import ErrorAlert from "~/components/ErrorAlert";
 import { User } from "~/lib/api/user";
 
 export const meta: MetaFunction<typeof loader> = ({ data }) => {
-	return [{ title: `${data?.meta.title || "Log in"} - pronouns.cc` }];
+	return [{ title: `${data?.meta.title || "Log in"} • pronouns.cc` }];
 };
 
 export const shouldRevalidate: ShouldRevalidateFunction = ({ actionResult }) => {