Guard that ensures ready is signaled even if task panics or is cancelled.
Created via ReadyGuard::new(), signals on drop if not already signaled.
IMPORTANT: After calling signal(), the Arc is released to allow
proper cleanup when the parent stream is dropped.
A readable stream handle - can be subscribed to and piped from.
A typed, heterogeneous relay with lossless delivery and completion tracking.
Relay namespace for creating channels.