Function attach_display 

pub fn attach_display(handle: OwnedDisplayHandle) -> Option<ClipboardAttachment>

Attach the native clipboard to the runner’s Wayland display, so copies go through the connection that owns the focused surface — the compositor only accepts set_selection from that one.

The runner keeps the returned guard until close. A no-op when the host installed its own clipboard, already attached, or is not on Wayland.