docs(claude): Add CLAUDE guidance file (#55)

- Add CLAUDE.md describing project overview, development commands,
testing architecture, CI/CD, and guidelines for Claude Code to interact
with this repository
- Update .gitignore to ignore .claude artifacts generated by Claude

Fix escaping of backslashes in regex and test cases (#53)

Support negative byte values in FS::format method (#50)

Reorganize PHP extension requirements in composer.json (#49)

Update PHP 8.3 (#47)

New function `Arr::getSchema()` (#45)

Added percentile and median functions (#43)

Release v7 (#40)

Minimal PHP version is 7.4 (#31)

Fixed failed test