isLiteRtLmFilename function
Whether filename ends in .litertlm, compared ASCII case-insensitively
(model.LiteRTLM matches; only A–Z fold, so a non-ASCII look-alike
never does).
The one predicate core and engine packages use to tell a .litertlm
bundle from any other model file.
Implementation
bool isLiteRtLmFilename(String filename) =>
_hasAsciiSuffix(filename, _liteRtLmSuffix);