SpharaPy v1.3.0 – Spectral Filtering & Major Documentation Update

This release introduces a substantial expansion of SpharaPy’s spatial
filtering capabilities together with a comprehensive overhaul of the
documentation and examples.

Highlights:
- New SPHARA-domain spectral filters (ideal, Gaussian, Butterworth)
- Support for low-pass, high-pass, and band-pass spatial filtering
- Physically interpretable spatial frequencies (1/mm) and wavelengths (mm)
- Updated EEG examples and extended Sphinx-Gallery tutorials
- Revised mathematical notation and expanded glossary
- Modernized packaging and fully warning-free documentation build

This version is recommended for all users.

Please see CHANGELOG.md for full details.