v0.19.0: Summarize any file

Summarize now works on every file, not just text: PDFs (read with their figures and scans), images (SVG/AVIF/BMP/ICO converted in the browser), and Word, Excel, PowerPoint, OpenDocument and EPUB files. Those office files can now be opened in the workspace as a card with Summarize and Download; older .doc/.xls/.ppt files work on a best-effort basis. API: POST /api/v1/summaries/document also takes { path, data (base64), mime? }. Same 10 free a week, then pay as you go.