Fix issue 171: avoid double dispatch for wildcard event

[gabewillen]

Summary:

• fix wildcard mapping so wildcard event does not participate in anonymous event dispatch
• add regression test test/ft/issue_171.cpp covering the upstream repro
• register test_issue_171 in test/ft/CMakeLists.txt

Reference:

• Transition with event<_> is invoked twice by one event boost-ext/sml#171

[Copilot]

Pull request overview

This PR fixes issue boost-ext#171 where wildcard events (event<_>) were being dispatched twice - once for the wildcard handler and once for the anonymous event dispatch mechanism. The fix ensures that anonymous events, which are internal events used for automatic transitions, do not participate in wildcard event dispatch.

Changes:

• Added template specialization for anonymous events to bypass wildcard event dispatch logic
• Added regression test to verify wildcard events are only fired once
• Registered the new test in the CMake build system

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
include/boost/sml.hpp	Added get_event_mapping_impl_helper specialization for anonymous to prevent double dispatch with wildcard events
test/ft/issue_171.cpp	Added regression test verifying wildcard events fire exactly once, not twice
test/ft/CMakeLists.txt	Registered the new test_issue_171 test executable and test case

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