Release 1.0.0 and fix sdist packaging

[nikhilvdev]

This change marks the first stable 1.0.0 release by bumping the package version and updating the development status classifier to Production/Stable. It also fixes a packaging issue in the sdist build by replacing the implicit file inclusion with an explicit allowlist, preventing local machine-specific artifacts like .hypothesis from being bundled into releases. The changelog was updated to document the release and the packaging verification work.

Summary

Checklist

• ruff check . passes
• mypy logquill passes (--strict on the public API)
• pytest passes, and new surface area has test coverage
• Public API additions are documented in README.md with a runnable example
• CHANGELOG.md has an entry under Unreleased
• If this touches the cross-language contract (levels, logger methods,
  record shape, transport/plugin contracts, config shape) shared with
  logquill-js, a matching tracking issue/PR is opened there

Scope