Add the split-screen auth shell, switch prompt, and password toggle

web/frontend/app/features/auth/components/ShowPasswordToggle.tsx

@@ -0,0 +1,18 @@
+import { Button } from '@headlessui/react';
+
+interface ShowPasswordToggleProps {
+    shown: boolean;
+    onToggle: () => void;
+}
+
+const ShowPasswordToggle = ({ shown, onToggle }: ShowPasswordToggleProps) => (
+    <Button
+        type="button"
+        onClick={onToggle}
+        className="inline-flex min-h-11 items-center self-start text-[0.9375rem] font-semibold text-secondary hover:underline"
+    >
+        {shown ? 'Hide password' : 'Show password'}
+    </Button>
+);
+
+export default ShowPasswordToggle;