[CanReader]

• bump to 0.3.1 and restore the plain description

What this changes

Sets the crate version to 0.3.1 and puts the description back to "A small deep learning library in Rust with optional CUDA kernels" in Cargo.toml and the README.

Why

The v0.3.1 tag was pushed with Cargo.toml still on 0.3.0, so the release workflow's tag check stopped it and nothing was published. The version has to match before the tag is recreated. "Robust" was also not accurate, and CUDA is optional.

How it was verified

• cargo test passes
• cargo clippy --all-targets -- -D warnings is clean
• Ran cuda_parity on a GPU
• Trained an example in --release
• No GPU here, CUDA side not runtime tested

Version and description only. cargo publish --dry-run passes.

Checklist

• Every new or changed backward rule has a gradcheck case
• Every new kernel has a cuda_parity case
• tensor/ops and autograd/ops still mirror each other
• Public items have /// docs