dsh-wsl-cred: Git Credential Diagnostics and Security Guidance for WSL Environments

`dsh-wsl-cred` is a DeepSeek Harness plugin for diagnosing Git HTTPS request failures in WSL. It checks credential presence and GCM configuration, provides security guidance, and strictly protects privacy by never leaking tokens or passwords. It depends on the `dsh-wsl-kit` suite and requires the environment to meet specific Kit Set and model configuration requirements. After installation, it can be tested via npm to resolve ambiguous WSL Git authentication configuration issues.