feat(pdf): add extract text, page numbers, crop, extract images operations

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

src/main.js

@@ -1432,6 +1432,25 @@ function createMenu() {
           label: 'Add Watermark...',
           click: () => showPDFEditorDialog('watermark'),
         },
+        {
+          label: 'Add Page Numbers...',
+          click: () => showPDFEditorDialog('pageNumbers'),
+        },
+        {
+          label: 'Crop Pages...',
+          click: () => showPDFEditorDialog('crop'),
+        },
+        {
+          type: 'separator',
+        },
+        {
+          label: 'Extract Text...',
+          click: () => showPDFEditorDialog('extractText'),
+        },
+        {
+          label: 'Extract Images...',
+          click: () => showPDFEditorDialog('extractImages'),
+        },
         {
           type: 'separator',
         },
@@ -1463,7 +1482,7 @@ function createMenu() {
               title: 'About PDF Editor',
               message: 'PDF Editor',
               detail:
-                'Comprehensive PDF editing capabilities powered by pdf-lib.\n\nFeatures:\n• Merge multiple PDF files\n• Split PDF into separate files\n• Compress PDF to reduce file size\n• Rotate pages (90°, 180°, 270°)\n• Delete unwanted pages\n• Reorder pages\n• Add text watermarks\n\nSecurity Features:\n• Password protection (encryption)\n• Remove passwords (decryption)\n• Set document permissions\n\n100% offline and open-source.',
+                'Comprehensive PDF editing capabilities powered by pdf-lib and pdfjs-dist.\n\nFeatures:\n• Merge multiple PDF files\n• Split PDF into separate files\n• Compress PDF to reduce file size\n• Rotate pages (90°, 180°, 270°)\n• Delete unwanted pages\n• Reorder pages\n• Add text watermarks\n• Add page numbers\n• Crop pages\n• Extract text\n• Extract embedded images\n\nSecurity Features:\n• Password protection (encryption)\n• Remove passwords (decryption)\n• Set document permissions\n\n100% offline and open-source.',
               buttons: ['OK'],
             });
           },