Optimise CI: run clang-format check as a gate for slower jobs

[stivlo]

The clang-format check completes in ~1 minute, while the build/test jobs take significantly longer. If a PR has formatting issues, there's no point waiting for the slower jobs to finish — we already know the PR can't be merged.

Suggestion: add needs: clang-format to the unit-tests, integration-tests, clang-tidy, and build-unsigned jobs in build.yml so they only run after the format check passes. This would save CI minutes and provide faster feedback on formatting errors.

Additionally, a pre-commit hook script could catch formatting issues locally in seconds, before they even reach CI. Each developer would need to install it manually after cloning (instructions would be added to Docs/Building.md). The CI job would remain as a safety net.

Happy to submit a PR if this sounds reasonable.

[mikekazakov]

I agree that running clang-format checks on CI first is a good idea.
Maybe integration-tests, clang-tidy and build-unsigned should also be gated, by unit-tests.
So maybe 3 CI stages would be good:

• clang-format
• unit-tests X 4
• integration-tests, clang-tidy and build-unsigned

If you could prepare a PR for this adjustment it would be awesome.

Frankly a local pre-commit hook sounds too heavy-weight, I think that would be an overkill...