Name-tree keys are PDF text strings, so encode named destinations with
stringToAsciiOrUTF16BE when writing the /Dests tree; otherwise a non-ASCII
name (e.g. "名") is truncated to a single byte and lost on round-trip. Sort
the name/number tree by byte value rather than localeCompare, matching the
order used when the tree is read back.
Apply the same encoding to deduplicated /EmbeddedFiles names: those are
rebuilt from a decoded display string, so a non-ASCII attachment name would
otherwise be corrupted when its duplicate is written.