Fix 1-4 interpolation for core-dummy interactions

[jthorton]

This fixes the treatment of 1-4 interactions between core and dummy atoms and extensive tests to the hybrid topology factory to ensure they are handled correctly.

Checklist

• All new code is appropriately documented (user-facing code must have complete docstrings).
• Added a news entry, or the changes are not user-facing.
• Ran pre-commit: you can run pre-commit locally or comment on this PR with pre-commit.ci autofix.

Manual Tests: these are slow so don't need to be run every commit, only before merging and when relevant changes are made (generally at reviewer-discretion).

• GPU integration tests
• example notebook testing
• packaging tests: run this for any large feature PRs or PRs that add test data.

Developers certificate of origin

• I certify that this contribution is covered by the MIT License here and the Developer Certificate of Origin at https://developercertificate.org/.

[jthorton]

pre-commit.ci autofix

[jthorton]

The 4 tests introduced to show that 1-4 interactions between the core-dummy atoms has failed as expected https://github.com/OpenFreeEnergy/openfe/actions/runs/22312817357/job/64549319567?pr=1856#step:11:6546. Now turning on the setting by default which should fix the tests.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.13%. Comparing base (f6cb213) to head (faadb9f).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1856      +/-   ##
==========================================
- Coverage   95.20%   93.13%   -2.07%     
==========================================
  Files         204      204              
  Lines       17629    18572     +943     
==========================================
+ Hits        16783    17297     +514     
- Misses        846     1275     +429     

Flag	Coverage Δ
fast-tests	93.13% <100.00%> (?)
slow-tests	?

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[github-actions]

No API break detected ✅