Standalone task execution, executors, timers, and process lifecycle.

This unpublished extraction owns the canonical stlab/concurrency/task.hpp, executor and timer headers, and stlab/pre_exit.hpp. Public APIs retain their stlab:: spellings. Futures, channels, await helpers, and serial queues remain in STLab, which publicly depends on this package.

Link stlab::execution from source or after find_package(stlab-execution CONFIG REQUIRED). Rebuild all consumers: independent C++ inline namespaces do not promise old binary compatibility. The v2 C runtime ABI and task-storage guards are preserved.

concurrency documents scheduling primitives; pre_exit documents process lifecycle. The README describes independent configuration, installation, local overrides, and publication blockers. There is no published execution documentation site yet.

License: Boost Software License 1.0.