Use the same hash factory in a using scope with explicit resets

Replace known parameterless MD5 CSP or SHA Managed/CSP construction in a closed using block or declaration with its same-algorithm factory, retaining ComputeHash and explicit Initialize calls with the actual BCL reset descriptor. Retain optional direct terminal Clear/Dispose and existing using disposal. Skip post-cleanup use, nested cleanup, state/streaming operations, identity, escape/capture, async/iterators and conditional snapshots. Opt-in modern-.NET compatibility port; no algorithm, encoding or format change.