address issue 200: use stop_callback_traits to support std::stop_token

[dietmarkuehl]

No description provided.

[Copilot]

Pull request overview

Updates the library’s stoppable-token infrastructure so std::stop_token can satisfy the stoppable_token concept (Issue 200).

Changes:

• Introduces detail::stoppable_token_traits to abstract how a token provides its stop-callback type (with a specialization for std::stop_token).
• Refactors stoppable_token and stop_callback_for_t to use the new traits instead of directly requiring Token::callback_type.
• Adds a regression test for std::stop_token and wires it into the test CMake list.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/beman/execution/issue-200.test.cpp	Adds compile-time assertion that std::stop_token models stoppable_token.
tests/beman/execution/CMakeLists.txt	Registers the new Issue 200 test target.
include/beman/execution/detail/stoppable_token.hpp	Updates stoppable_token concept to validate callback support via stoppable_token_traits.
include/beman/execution/detail/stop_token_traits.hpp	New traits header providing a generic mapping + std::stop_token specialization.
include/beman/execution/detail/stop_callback_for_t.hpp	Updates stop_callback_for_t alias to use stoppable_token_traits.

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[coveralls]

coverage: 92.63%. remained the same
when pulling 18c3e57 on issue-200
into a098f90 on main.