Adds the pq_signatures feature (one new dependency, ml-dsa 0.1.1, default
features off) and src/pq_sig.rs: the suite id-MLDSA65-Ed25519-SHA512 of
draft-ietf-lamps-pq-composite-sigs-19 (M' = Prefix || Label || 0 || SHA-512(M),
the ML-DSA half with the label as context, the Ed25519 half under WAI's strict
rule), the policy that requires hybrid, the hybrid JSON members and the shared
helper for records signed as wai:<domain>\x01 || JCS.
Before anything is built on it, the ML-DSA-65 implementation is checked
against the ACVP internal projections vendored in pq-conformance/acvp
(keyGen 25, deterministic sigGen 45 over three interfaces, sigVer 45), each
file pinned by SHA-256, and the composite against the draft's Appendix E
vector for this suite. Corpus, bin and test are stubs here.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
4ad02a0bcb