Adds four new PDFOperations: pdfExtractText (pdfjs-dist getTextContent),
pdfAddPageNumbers (reuses pdfWatermark's position-mapping logic, extracted
into a shared resolvePosition helper), pdfCrop (page.setCropBox against the
existing MediaBox), and pdfExtractImages (pdfjs-dist operator list +
paintImageXObject + sharp). Wired into executeOperation's switch and the PDF
editor dialog UI (4 new sections/toolbar buttons/menu items) with no new IPC
channel needed.
pdfjs-dist v5 is ESM-only, so it's loaded via dynamic import() of its
Node-friendly legacy build; Jest needs --experimental-vm-modules to support
that, so the test scripts now set NODE_OPTIONS accordingly via cross-env.
Amit Haridas
