dsh-text-lines: Text Line Deduplication/Sorting/Statistics

`dsh-text-lines` is a DSH plugin implemented in pure Node.js, providing lightweight local text processing capabilities. It requires no network connection and supports three basic operations: text-line deduplication, sorting, and statistics. Once installed, it can be invoked directly in a session. Because the plugin runs code with process-level privileges, users should review the source code before installation to ensure security.