Constructor argument of `cancel_after_timer` is missing

https://github.com/boostorg/asio/blob/a7dc25b4cb6c49a6946d86ea20664f1027203225/include/boost/asio/cancel_after.hpp#L161

Second constructor argument (`basic_waitable_timer& timer`) for `cancel_after_timer,
Clock, WaitTraits, Executor>` is missing here.

Open include/boost/asio/cancel_after.hpp at line 161 and compare the cancel_after_timer constructor with the signature described in the issue. Confirm the missing basic_waitable_timer argument and verify the resulting constructor declaration matches its intended parameters; run the relevant Asio tests to ensure the header still builds.

Written by the indexing model from the issue text.