Consistent developer tooling; refactor formatting CI

[ZedThree]

TL;DR:

CI will now fail on unformatted commits. Instead, run automatic formatting when you make commits:

uv sync --only-dev         # Install consistent versions of clang-format, etc
uv tool run prek install   # Install pre-commit hooks

---

clang-format and clang-tidy are both essential tools for keeping the code clean and catching potential bugs, but the way they are currently run in CI is getting a bit annoying. Namely:

1. The last CI check ends up being the automated commit applying formatting, which always passes, and hides the actual test results
2. The formatting moves things around and the clang-tidy comments end up in the wrong places
3. Adding clang-format commits to .git-blame-ignore-revs keeps git blame clean but makes merge conflicts much more likely, requiring more merges to fix them + another round of CI
4. Inconsistent versions of clang-format on dev machines and CI means formatting can flip-flop back and forth

This PR tries to fix these issues by:

• making the CI check fail if it has to do any formatting
• adding config so we can all get consistent versions of the tools locally and on CI
• adding pre-commit config so that formatting can run when making commits, meaning code should always be formatted
• no automated commits, and commits always be correctly formatted means not having to add commits to .git-blame-ignore-revs

[ZedThree]

I'm going to make a separate PR into this one applying all the formatting rules across everything -- turns out we have a lot of trailing whitespace

[dschwoerer]

Looks good, thanks 👍

[dschwoerer]

I'm going to make a separate PR into this one applying all the formatting rules across everything -- turns out we have a lot of trailing whitespace

Maybe we should first try to reduce the number of open PRs, to avoid to many conflicts?

[ZedThree]

I've expanded the docs on this further to make things clearer about how things work.

I've also switched clang-tidy-review to post annotations instead of comments. We'll see how that fairs

[ZedThree]

Just a heads up once this gets merged and people start using it: you can pass git commit --no-verify to temporarily skip the pre-commit hooks. This might be necessary if switching between branches without this branch merged

[dschwoerer]

    git clang-format origin/next

next may be an old, stale local branch. But then, origin may also be there own fork, which may also be outdated ...