Single-threaded asynchronous runtime infrastructure for ntex.
A [System] owns the runtime configuration and coordinates one or more
[Arbiter] execution threads. Each arbiter runs local futures on its own
thread, allowing tasks to use types that are not Send.
Use [System::build()] to configure a system, [spawn()] to start a local
task, and [spawn_blocking()] for blocking work.
Runtime backends are selected with Cargo features:
- no runtime feature uses the native ntex runtime
tokiouses the Tokio-based runtime adaptercompiouses the Compio-based runtime adapter