RtfDocumentWriter

Serializes an RtfDocument to a charset-free RTF string.

Output is 7-bit ASCII: every code unit above 127 is emitted as a signed \uN escape with a ? fallback (see appendRtfEscaped). The font and color tables are derived from the fonts and colors actually referenced by the document (plus RtfDocument.defaultFont); each run is wrapped in its own {...} group so character formatting cannot leak between runs.