Add Python 3.14 support

[AndreVale69]

Motivation

Python 3.14 is approaching stable release, and the project should officially support and test against it.
This ensures long-term compatibility and avoids last-minute breakages once 3.14 becomes widely adopted.

Scope

This issue tracks the work required to officially support Python 3.14, including package metadata,
documentation, and Continuous Integration (CI) coverage.

Tasks

• Update package metadata
  • Ensure requires-python remains >=3.9
  • Add Python 3.14 Trove classifier in pyproject.toml
• Update documentation
  • Mention Python 3.14 in the list of supported Python versions (README / docs)
• Extend CI matrix
  • Add Python 3.14 to the GitHub Actions test matrix
  • Ensure tests run successfully on ubuntu-latest (minimum required)
• Validation
  • All existing tests pass on Python 3.14
  • No behavior regressions compared to previously supported versions

Acceptance Criteria

• CI runs automatically on Python 3.14 for pull requests and main branch
• Package metadata correctly advertises Python 3.14 support
• Documentation clearly states that Python 3.14 is supported

Notes

• Python 3.14 support should be treated as fully supported, not experimental
• Any incompatibilities discovered during CI should be addressed in follow-up issues