docs: add copilot instructions file

[zerone0x]

Summary

Fixes #6

Adds .github/copilot-instructions.md pointing Copilot users to /CLAUDE.md and updates CHANGELOG.

Changes

• add .github/copilot-instructions.md referencing /CLAUDE.md
• update CHANGELOG.md under [Unreleased]

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[FlorianBruniaux]

Thanks for this @zerone0x, the content looks good. The CHANGELOG entry and the .github/copilot-instructions.md file are exactly what was discussed in #6.

One thing to fix before we can merge: the PR has a merge conflict (CHANGELOG.md), probably because several releases landed on main since you opened this. A quick rebase should sort it:

git fetch upstream
git rebase upstream/main
# resolve conflict in CHANGELOG.md if needed, then:
git push --force-with-lease

Once rebased, I'll merge it.