dratify 0.1.7 fixes a soundness hole, and says why PySAT's CaDiCaL proofs fail

dratify 0.1.6 fixed the README’s PySAT example — it loaded formulas with PySAT’s own parser, which stops at the % line every SATLIB file ends with — and closed a release path that let workflow_dispatch publish from a branch, with the pypi and crates environments now restricted to v* tags (108dd50, 5d0bb47). 0.1.7 is the security fix: three checker bugs found while tracing why PySAT’s CaDiCaL proofs do not verify, one of them a soundness hole where the pure-Python checker accepted refutations of satisfiable formulas when a list of steps held a negative literal — reachable through check_proof, though not from cdclkit’s own solver, and text proofs were never affected — alongside an unbounded literal that could size arrays for 10¹¹ variables and two false rejections, both checkers refusing valid proofs in which a lemma arrived unit at the root (61165f9). The PySAT failure itself is not the checker’s: the binding reads every CaDiCaL proof before flushing it, and with the documented workaround all four CaDiCaL versions verify 50 of 50, where glucose and Lingeling already did (2823854).