Merging dev to master

[astrolamb]

This pull request introduces significant improvements to red noise and chromatic signal modeling by adding new FFT-based time-domain basis functions, updates documentation to explain their usage, and modernizes Python version support and CI configuration. It also refactors parts of the enterprise.pulsar interface for improved compatibility and flexibility, and makes minor code cleanups.

Red noise and chromatic signal modeling enhancements:

• Added new FFT-based time-domain basis functions: create_fft_time_basis, create_fft_time_basis_dm, and create_fft_time_basis_chromatic in gp_bases.py, enabling more realistic modeling of red noise and chromatic signals. These functions provide a rank-reduced, time-domain alternative to traditional Fourier basis methods. [1] [2] [3]
• Updated documentation with a new tutorial (docs/fft.rst) describing the new FFT-based modeling capabilities, usage examples, and parameter explanations. This is linked from the main docs index. [1] [2]

Python and CI modernization:

• Updated the minimum supported Python version to 3.10 and expanded CI testing to Python 3.10–3.14, dropping support for 3.8 and 3.9. Updated GitHub Actions to use newer versions of actions and improved macOS SuiteSparse handling. [1] [2] [3] [4]

enterprise.pulsar interface and refactoring:

• Replaced direct type checks with interface checks for PINT and Tempo2 objects, improving compatibility with custom or wrapped objects. [1] [2]
• Refactored filter_data to allow filtering by a mask and/or time range, making data selection more flexible. [1] [2]
• Updated the method for loading pulsar distance data to use importlib.resources for better package data handling.

Maintenance and cleanup:

• Updated pragma comments for Python version conditionals in deflation/inflation logic.
• Minor code and import cleanups in several files. [1] [2] [3] [4]

These changes collectively modernize the codebase, enhance modeling flexibility, and improve documentation for new features.