dsh-test-coverage: Test Coverage Report Parsing and Analysis

dsh-test-coverage is a DeepSeek Harness (DSH) plugin designed to transform messy code coverage reports (supporting multiple formats such as LCOV, Cobertura, and Istanbul) into structured data. Implemented purely in Node.js with no external dependencies, it allows you to view overall project coverage and pinpoint the exact uncovered line ranges in a specified file, sorting by coverage from lowest to highest to help developers quickly identify gaps and write additional tests.