Backport CS* tightening

[flying-sheep]

So the accurate types are used in a soon-to-be-released anndata version.

I also did a few things I missed in the original review. Getting these into main in a separate PR: #1890

TODO:

• should one fix be backported? (chore): adopt scientific python deprecation schedule #1768 (review)

  (no, breaking change)

• only changes to types and tests

[codecov]

Codecov Report

Attention: Patch coverage is 92.59259% with 2 lines in your changes missing coverage. Please review.

Project coverage is 83.75%. Comparing base (f996bb1) to head (5863c6d).
Report is 28 commits behind head on 0.11.x.

Files with missing lines	Patch %	Lines
src/anndata/_core/merge.py	83.33%	1 Missing ⚠️
src/anndata/compat/__init__.py	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           0.11.x    #1889      +/-   ##
==========================================
- Coverage   86.20%   83.75%   -2.46%     
==========================================
  Files          41       41              
  Lines        6250     6255       +5     
==========================================
- Hits         5388     5239     -149     
- Misses        862     1016     +154     

Files with missing lines	Coverage Δ
src/anndata/_core/aligned_mapping.py	93.41% <100.00%> (-0.03%)	⬇️
src/anndata/_core/anndata.py	82.47% <100.00%> (ø)
src/anndata/_core/index.py	93.60% <100.00%> (ø)
src/anndata/_core/raw.py	75.88% <100.00%> (-4.26%)	⬇️
src/anndata/_core/sparse_dataset.py	92.14% <100.00%> (ø)
src/anndata/_io/h5ad.py	92.68% <ø> (ø)
src/anndata/_io/specs/lazy_methods.py	97.80% <ø> (ø)
src/anndata/_io/specs/methods.py	88.10% <100.00%> (-0.42%)	⬇️
src/anndata/abc.py	100.00% <100.00%> (ø)
src/anndata/typing.py	100.00% <ø> (ø)
... and 2 more

... and 4 files with indirect coverage changes

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[ilan-gold]

Aside from the failing CI, looks good