Run pytest with coverage reporting to identify and eliminate untested code lines.

• ›Generates annotated source files in cov_annotate/ directory, with ! markers indicating uncovered lines
• ›Supports module-specific coverage checks via --cov=module_name and targeted test runs on specific test files
• ›Workflow: run coverage, review annotated files for uncovered lines, write tests to cover gaps, repeat until 100% coverage achieved