fix: add missing sniffio dependency

[botana-te]

fixes: #61

---

Note

Low Risk
Dependency-only change; primary risk is minor install/compatibility issues if sniffio version constraints conflict in downstream environments.

Overview
Adds the missing runtime dependency sniffio>=1.3.1 to pyproject.toml so environments installing the package pull it in.

Updates uv.lock accordingly so the lockfile and published requires-dist metadata include sniffio.

^{Written by Cursor Bugbot for commit 5eb95be. This will update automatically on new commits. Configure here.}