Exclude mlx-c submodule and non-essential dirs from crate package

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: juntao

Cargo.toml

@@ -7,6 +7,7 @@ description = "Rust implementation for the CohereLabs/cohere-transcribe-03-2026
 repository = "https://github.com/second-state/cohere_transcribe_rs"
 keywords = ["speech-to-text", "transcription", "asr", "mlx", "libtorch"]
 categories = ["multimedia::audio", "command-line-utilities"]
+exclude = ["mlx-c/", ".github/", "tests/", "models/", "tools/"]
 
 [[bin]]
 name = "transcribe"