dratify v0.1.4/v0.1.5: published speed figures replaced with numbers anyone can reproduce

dratify tagged v0.1.4 and v0.1.5 after an audit of its published numbers: the README’s speed table came from CNF files that are not in the repository, and its “~18x” was the top of a range quoted as the typical value. A committed benchmark script (bench/repro.py) now produces figures anyone can reproduce — a second run held the geometric mean at ~15x while individual ratios moved between 11x and 22x, so the release quotes the mean and states the spread as a spread. The same pass (c34c31b) added a fuzz workflow and stopped error messages from reporting version skew in the vocabulary of an unrelated project’s module.