The default with_tkinter=True pulls in tk/tcl/xorg, and xorg/system
requires X11 dev packages that Conan won't auto-install in CI
(tools.system.package_manager:mode defaults to check). python_effect
only needs the embeddable Python C API, so tkinter isn't needed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>