Introduced core RTF document components, such as RTFDocument, RTFPage,
RTFTitle, RTFColumnHeader, and RTFBody. These classes establish the
foundation for composing structured RTF documents with a text encoding
pipeline. Use Pydantic for data validation.
Implemented string width calculation using Pillow with metric-compatible fonts.
This will be incorporated in the pagination and layout algorithms in
future releases.
Implemented a LibreOffice-based document converter for RTF to PDF conversion
with automatic LibreOffice detection mechanisms under Linux, macOS, and Windows.