Track and plot pace of changes (pace_of_changes data + pace_of_changes.png/.dat) — gitstats
Add PDF report generator using fpdf2 with embedded charts (PDFReportCreator) — gitstats
Add repository size calculation and getter (repository_size_mb + getRepositorySize) — gitstats
Add last-30-days and last-12-months activity summaries and accessors (last_30_days_*, last_12_months_*) — gitstats
Add SLOC-per-extension breakdown on lines page and related data writers — gitstats
Add commit timing / external-command timing and --debug/--verbose tracing in runner — gitstats
Chores

Update README with usage, options, dependencies, outputs, and troubleshooting — README.md
Replace counting patterns with defaultdict(int) for robustness (DataCollector fields) — gitstats
Fix multirepo tags isolation (ensure tags cleared/isolated per repo) — gitstats
Initialize author entries consistently to avoid KeyError (author info structure) — gitstats
Generate and keep consistent .dat/.plot gnuplot artifacts and improve createGraphs hygiene — gitstats

This README provides an overview of the gitstats3 project, including features, prerequisites, installation instructions, and usage examples.