Matten Rust library wraps up with companion crates and migration advice

The final post in a series on the Rust tensor library matten introduces three companion crates: matten-ndarray for bridging to ndarray, matten-mlprep for preprocessing helpers, and matten-io for serialization. The author also discusses when to stop using matten and migrate to more mature tools. These crates are production-ready for proof-of-concept work but not intended for high-performance production use.