dsh-sql-format: SQL Formatting

`dsh-sql-format` is a DeepSeek Harness client plugin that formats messy SQL strings into standard, well-structured text with capitalized keywords. It only handles presentation-level formatting and does not make database connections or perform semantic analysis. Users can enable the plugin by running an install command and configuring `package.json`; after installation, they can call the `format_sql` function in a session to format SQL. Note that this plugin is implemented in Node; installation runs local code, so be sure to review its source code and license.