docs: switch to sphinx-exec-jupyter

[flying-sheep]

It’s a bit slower (212 sec → 274 sec) but all docs pages are run in isolation and the docs logs aren’t spammed with warnings that happen during plot execution.

Also it locally caches the plot code execution, so things should be faster locally with a populated cache.

• Closes #
• Tests included or not required because:

• Release notes not necessary because: internal change

TODO:

• add mode that only runs each page in isolation, not each code block

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.72%. Comparing base (68eeb6a) to head (07c29d0).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4182   +/-   ##
=======================================
  Coverage   79.72%   79.72%           
=======================================
  Files         120      120           
  Lines       12833    12833           
=======================================
  Hits        10231    10231           
  Misses       2602     2602           

Flag	Coverage Δ
hatch-test.low-vers	78.78% <ø> (ø)
hatch-test.pre	79.59% <ø> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/scanpy/metrics/_metrics.py	97.14% <ø> (ø)
src/scanpy/plotting/_anndata.py	85.42% <ø> (ø)
src/scanpy/plotting/_dotplot.py	94.87% <ø> (ø)
src/scanpy/plotting/_matrixplot.py	96.51% <ø> (ø)
src/scanpy/plotting/_preprocessing.py	86.27% <ø> (ø)
src/scanpy/plotting/_qc.py	86.11% <ø> (ø)
src/scanpy/plotting/_stacked_violin.py	85.78% <ø> (ø)
src/scanpy/plotting/_tools/__init__.py	76.17% <ø> (ø)
src/scanpy/plotting/_tools/paga.py	64.26% <ø> (ø)
src/scanpy/plotting/_tools/scatterplots.py	83.41% <ø> (ø)
... and 2 more