Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01HgnbPwSoRGNH7LHsDUmRpk
PDF viewer (render/search/text-select/thumbnails/outline) and annotation engine (Highlight/Underline/Strikeout/Square/FreeText/Note) over PDFium + lopdf, with Unicode font embedding for Vietnamese text and undo/redo.