Add CI, and declare scipy

[remislp]

EKDIST was the last repository in the stack without CI. That mattered more once
it stopped being self-contained: it now takes its log-binning from dcio, so a
change over there can break it here and nothing would say so.

The dcio wrinkle

dcio is not on PyPI, so every job installs it from git before installing
EKDIST — otherwise pip install -e . fails on an unresolvable requirement:

pip install git+https://github.com/DCPROGS/dcio@master
pip install -e .

That step is the first thing to revisit when dcio is published.

scipy was never declared

ekplot, errors and exponentials all import scipy. install_requires
named numpy and matplotlib only. An editable install into an environment that
already has scipy cannot reveal that — only a clean one can, which is what the
clean-install job does: build into an empty virtualenv, then import every
module from outside the source tree.

Declared it. Also added python_requires='>=3.11' — setup.py named no floor,
but dcio's requires-python sets one in practice, and an inherited constraint
is better written down than discovered.

Matrix

3.11 / 3.12 / 3.13 on Linux, plus macOS and Windows. MPLBACKEND=Agg is set
explicitly rather than left to backend autoselection, since ekplot imports
matplotlib.pyplot at module level and the runners have no display.

One extra gate: the record files are read by relative path from the repo
root ("./tests/AChsim.scn"), so a step checks they are present before the
suite runs.

36 passing.

🤖 Generated with Claude Code