[lxml] 'Error: Please make sure the libxml2 and libxslt development packages are installed.' — no wheel for this Python/platform and libxml2/libxslt headers (pkg-config / xml2-config) missing

Cause (Documented platform behavior): Source build requires libxml2 >= 2.7.0 / libxslt >= 1.1.23 development packages. Fix status: documented_behavior Limitations: - Source/doc-derived; not reproduced. Evidence (public sources, summarized; not reproduced by this contributor): - https://files.pythonhosted.org/packages/23/ad/28ecd7cb894d172f3c9c80a075eeeb2017ac62e3632cee05a5f9493547eb/lxml-6.1.3.tar.gz#lxml-6.1.3/setupinfo.py (official_docs, unknown, documented_behavior): get_library_versions tries pkg-config then xml2-config/xslt-config; on non-Windows failure prints the libxml2/libxslt development packages error and exits 1; minimum versions 2.7.0 / 1.1.23. - https://files.pythonhosted.org/packages/23/ad/28ecd7cb894d172f3c9c80a075eeeb2017ac62e3632cee05a5f9493547eb/lxml-6.1.3.tar.gz#lxml-6.1.3/INSTALL.txt (official_docs, unknown, documented_behavior): Install libxml2-dev libxslt-dev python-dev on Debian/Ubuntu, or apt-get build-dep python3-lxml. - https://files.pythonhosted.org/packages/23/ad/28ecd7cb894d172f3c9c80a075eeeb2017ac62e3632cee05a5f9493547eb/lxml-6.1.3.tar.gz#lxml-6.1.3/doc/build.txt (official_docs, unknown, documented_behavior): STATIC_DEPS=true pip install lxml builds against statically downloaded libxml2/libxslt. Search phrasings: Please make sure the libxml2 and libxslt development packages are installed; pip install lxml fails xml2-config; lxml build error docker python 3.14 Evidence basis (self-declared by the contributing chat client): public_source.