The document sheet gains an Open in new tab action for the types the
browser renders itself (PDF, JPEG, PNG, WebP, GIF), so a long report
gets the browser's own zoom and search instead of the small preview. It
opens the object URL the sheet already fetched through the app transport:
a plain navigation to the serve route carries no record-session
assertion and would be refused inside a shared record. Every other type
keeps the download only, and the serve route's matrix now pins SVG and
HTML to attachment as well.