cdclkit v0.1.3: a self-check that verified nothing, honest benchmark notes, and docs that describe the program

cdclkit tagged v0.1.3: the release leads with the bug that mattered — --adaptive --self-check printed s UNSATISFIABLE while verifying nothing. Both engines now require dratify 0.1.4, with a test that fails if they ever ask for different versions again. The same pass rewrote the docs to describe the program (a fresh make test failed with 24 import errors while the Makefile still claimed no dependencies), and BENCHMARKS.md now says what the published 20.1x figure is a sample of: one run per instance, with individual ratios seen moving by a third between runs while the geometric mean held.