Fix Overture release id parsing and pin affine<3 (main fails since August)

[Zhonghao Zhang (Zhonghao1995)]

Replaces #505: the same two commits, now on a branch in this repository so that CI has access to the Codecov token and does not need approval for each run.

Closes #502 and #503.

Problem observed

On a fresh pip install -e . of main (f0c18be) on 2026-09-04, macOS 26.6.2, Python 3.11.15, every run failed twice over:

1. The buildings download:

   FileNotFoundError: overturemaps-us-west-2/release/https:/stac.overturemaps.org/2026-08-19.0/theme=buildings/type=building/
   

   _get_latest_s3_url takes Path(href).parent of the newest child link in the Overture STAC catalog; those hrefs are absolute URLs now, so the release id came out as https:/stac.overturemaps.org/2026-08-19.0 and was then cached in .cache/overture_release.json for 72 hours.
2. Once past that, clip_to_catchments:

   numba.core.errors.TypingError: ... Cannot determine Numba type of <class 'affine.Affine'>
   

   affine 3.0 (released 2026-08-08) turned Affine from a namedtuple into a plain class, and the @njit function pyflwdir.dem.slope that geospatial_utilities calls with the raster transform can no longer type it. pyflwdir 0.5.12 has not adapted yet.

Both come from upstream changes in August, so main currently fails the notebook runs in CI as well; the last green run on main predates them. The two fixes are in one PR because the notebooks need both to get through: with only one of them CI fails on the other error (that is what #505 and #506 showed separately).

Changes

• Extract the Overture release id with a regex (\d{4}-\d{2}-\d{2}\.\d+) from the href instead of taking the parent path; the catalog ordering logic is unchanged. A cached entry whose release is not a well-formed id is ignored, so working directories that already hold the malformed cache recover on their own. Two mocked tests in tests/test_prepare_data.py, no network access.
• Pin affine<3 in pyproject.toml. The alternative is to pass a plain tuple to pyflwdir.dem.slope in geospatial_utilities (the numba kernel only indexes transform[0], [4] and [5]); happy to switch to that if you prefer a code change over a pin.

Checks

pytest tests/test_prepare_data.py -k s3_url (2 passed), the repository's pre-commit hooks, and with both changes the documentation's Andorra bounding box builds end to end again with affine 2.4.0.

[Codecov Comments Bot (codecov-commenter)]

Codecov Report

❌ Patch coverage is 75.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.28%. Comparing base (f0c18be) to head (658e365).

Files with missing lines	Patch %	Lines
src/swmmanywhere/prepare_data.py	75.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #507      +/-   ##
==========================================
- Coverage   87.34%   87.28%   -0.06%     
==========================================
  Files          23       23              
  Lines        2355     2360       +5     
  Branches      302      303       +1     
==========================================
+ Hits         2057     2060       +3     
- Misses        206      207       +1     
- Partials       92       93       +1     

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[barneydobson]

Happy with that Zhonghao Zhang (@Zhonghao1995) go ahead and merge! and thanks for your contributions ✨