fn dict_file_target_name(original: &str, lang: &str) -> Option<String>Expand description
Maps a ZIP entry filename to its renamed output filename <lang>.<ext>.
Recognised extensions (in priority order):
.dict.dz→Reader-Dict-<lang>.dict.dz.dict→Reader-Dict-<lang>.dict.index→Reader-Dict-<lang>.index
Returns None for any other extension.