mathlib-fp 2.3.1

Version 2.3.1 is a documentation patch release. It does not change Pascal source, numerical behavior, or public APIs. The numerical-evidence catalogue and platform qualification carry forward from 2.3.0.

Documentation

• Expanded and refreshed the Pascal numerical-library comparison, adding
  machine-learning and arbitrary-precision projects and describing each
  library's strengths, compiler support, and licensing in neutral terms.
• Replaced the comparison's gap-and-roadmap list with release-specific
  capability references.
• Preserved the v2.3.0 versioned documentation build as it moves into the
  historical release set.
• Carried forward the unchanged 2.3.0 numerical-evidence catalogue with its
  provenance recorded.