fix: correct pending_user_overlay type definition in Config (#20285)

The Config type incorrectly defined 'pending_user_overlay_description'
but the backend returns 'pending_user_overlay_content' and the
AccountPending.svelte component correctly accesses that property.

This fixes the type mismatch to align with the actual backend response.

Fixes #20284

src/lib/stores/index.ts

@@ -284,7 +284,7 @@ type Config = {
 	};
 	ui?: {
 		pending_user_overlay_title?: string;
-		pending_user_overlay_description?: string;
+		pending_user_overlay_content?: string;
 	};
 };