Characterize an entropy string into the structured model.
Returns a plain object with keys: encoding, scheme, role, qualifiers,
sizeBasis, sizeBits, parts, entropyType. Never throws for an in-range input:
an unrecognized input falls back to the UTF-8 -> base64url path (scheme=null,
role=null, sizeBasis="utf8", size measured over the ORIGINAL input bytes).
Characterize an entropy string into the structured model.
Returns a plain object with keys: encoding, scheme, role, qualifiers, sizeBasis, sizeBits, parts, entropyType. Never throws for an in-range input: an unrecognized input falls back to the UTF-8 -> base64url path (scheme=null, role=null, sizeBasis="utf8", size measured over the ORIGINAL input bytes).