Add argparse-based CLI parsing with repeatable --repo/-r (include) and
--exclude/-x (exclude) options. Filtering is case-insensitive substring
matching, applied post-fetch in collect_all() per ADR-005.
- parse_args() separated from main() for testability
- main(argv=None) accepts argv for test injection
- collect_all() gains optional include/exclude parameters
- 14 new tests (8 filtering + 6 CLI parsing/integration)
- All 51 tests pass, backward compatible (no args = v1.0.0 behavior)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
