Frozen ZIP raw member identity

Trap: checking ZipInfo.filename uniqueness looks right because zipfile presents decoded names, but NUL truncation, UTF-8 flags, Unicode-path extras, separators, case, and Unicode normalization can map distinct raw identities to one required member. Fix: inspect central-directory raw filename and extra-field bytes; reject NULs, malformed or duplicate path extras, unsafe paths, and normalized collisions before resolving required members, while retaining archive-count and expansion bounds.