Svelte 5 has deprecated the slot tag. So now you have to use children, but its not clear how to do this.

Here is an example of how to use the slot / children in the layout component.

<scriptlang="ts">let{children}=$props();</script>{@renderchildren()}

Before doing this you will see errors like:
"Using<slot> to render parent content is deprecated. Use{@render ...} tags instead"