lineage.tests.conftest

Test-session setup.

Several tests drive scipy/numpy linear algebra hard enough that BLAS's own thread pool competes with pytest-xdist's worker processes for cores, which slows the suite down rather than speeding it up. Pin each library to a single BLAS thread so the parallelism comes from xdist alone; this must happen before numpy/scipy are imported anywhere, so it lives at the top of the first conftest.py loaded.