Fix sign conventions in ZH NLO EW at CEPC/FCCee/LEP3/LCF

[ecelada]

This PR changes signs to dipole operators and OWWW in ZH production according to 2409.11466.

[ecelada]

green light from me

[jacoterh]

Thanks for all the work! In addition to the comments above, here one general comment. While reviewing I noticed that some operators changed only because of finite numerical precision. I have implemented a new pre-commit hook as part of a new PR #137 that enforces a fixed numerical precision up to 1e-12 relative precision, which is more than precise enough and is reproducible across different machines. This way we will no longer get unnecessary git diffs in operators that didn't actually change.

Doing this on this branch would create a much cleaner PR: #136. I have opened this only as an example. We can repeat it on this branch if we like.

Oh, and please update the title of the PR. It's not just LCF.