- Add `write_csv_weekly()` to output.py: writes entries from multiple
days as a single CSV with one header row, correct date per row
- Add `-w`/`--weekly` flag to csv subparser
- _cmd_csv branches on args.weekly: fetches week sections, formats
per-day date strings, calls write_csv_weekly; --raw is honoured
- Add TestWriteCsvWeekly with 6 tests
- Update README with weekly csv usage examples
- Add `to_csv_entries()` to output.py: converts raw rows to write_csv
entries one-for-one, without merging by (project, description)
- Add `--raw` flag to the csv subparser; _cmd_csv branches on it
- Add TestToCsvEntries with 6 tests
- Update README with --raw usage example
- Add .coverage and htmlcov/ to .gitignore
