Use PDF outline (bookmarks) for chapter titles and page ranges, then
extract text from per-page content streams via pdfcpu ExtractContent.
This avoids the indefinite hang caused by dslipak/pdf trying to resolve
custom font ToUnicode CMaps on publisher PDFs.
- parsePDF: decrypt → ExtractContent → Bookmarks → chaptersFromBookmarks
- chaptersFromBookmarks: flatten bookmark tree, skip front/back matter
(Cover, Insert, Title Page, Copyright, Appendix), assign page ranges
- extractTextFromContentStream: handle TJ arrays (concat literal strings,
skip hex glyph arrays and kerning numbers) + single Tj strings
- Falls back to paragraph-splitting when no bookmarks present
- Build verified; test PDF produces 9 chapters with proper titles
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