dsh-text-mask: Text Masking

`dsh-text-mask` is a purely local data masking plugin in the DeepSeek Harness ecosystem. It requires no internet connection or external services and uses Node.js to replace sensitive information in text, such as email addresses, mobile phone numbers, ID numbers, bank card numbers, IP addresses, and API keys, with masked values. Users can invoke it through the `mask_text` tool. Please note that the code runs locally; review the source code before use to ensure security and compliance.