v0.5.7

Published to crates.io as mfsk-core v0.5.7.

Release notes are auto-generated from merged PRs; see the crate's
CHANGELOG.md
for curated release notes.

Prebuilt mfsk-ffi-ft8 binaries (FT8 C ABI) are attached
below for users who want to drop the decoder into a non-Rust
project without setting up the cross-toolchain themselves —
see docs/EMBEDDED.md
for the integration guide.

Full Changelog: v0.5.6...v0.5.7