# T06: Add Category Filtering

Add the exact option `--category <NAME>` to `python3 -m ledger list`. Before comparing, strip surrounding whitespace from both the query value and the stored categories, and compare case-insensitively using Unicode `casefold`; output keeps the records' original category spelling. A category with no matches returns an empty result and exits successfully. Category filtering must compose with `--start-date` and `--end-date` — it must not bypass date filtering.

Keep behavior without the option and the public interfaces compatible; add tests and a short usage note; do not delete or modify existing tests or add runtime dependencies. Run `python3 -m unittest discover -s tests -v` and report the actual result.