Changelog for ppad-fixed-0.1.2

# Changelog - 0.1.2 (2025-12-27) * Fixes an API mistake made in the v0.1.1 release. - 0.1.1 (2025-12-27) * Contains miscellaneous hardening and API refinements to v0.1.1. - 0.1.0 (2025-12-21) * Initial release, supporting wide, wider, and secp256k1-related Montgomery-form words with supporting constant-time operations.