dsh-cet-score: CET-4/6 Score Estimation Plugin

DeepSeek Harness offers a local CET-4/6 score estimation plugin named `dsh-cet-score`. Fully implemented in Node.js, it requires no network requests and enables precise local score calculation. Installation takes only one command, and it can be used by invoking the `cet_score` tool. This tool is suitable for privacy-sensitive or offline environments, allowing quick score estimation.