MnemosyneC v0.9.10

BP137: honest substrate answer-cache -- exact-match + semantic (nomic-embed) serve at zero cost; birthday-frame false-serve class closed (Psionic semantic-or-nothing floor); MMLU answer-key contamination hard-gated; Layer2ProveIt fabricated numbers removed for an honest CTA to the live Prove-It panel; Ask input never locks. New feature paths default-OFF. SHA-256 e582698a535746358bce697aaecbb488f977ecae8dbeabdbebfff11efded7899. Unsigned build.