feat(pdfjs-viewer): add initial PDF.js viewer assets and configuration

Add initial set of PDF.js viewer files including:
- WASM binaries for PDF rendering
- Standard fonts and CMAP files for text rendering
- UI icons and SVG assets for toolbar buttons
- TypeScript declaration files
- Loading animation GIF
- Annotation icons and UI elements

This provides the base functionality for the PDF viewer including:
- Document rendering
- Navigation controls
- Zoom functionality
- Page display options
- Annotation tools
- Document properties

public/pdfjs-viewer/images/secondaryToolbarButton-firstPage.svg

@@ -0,0 +1,3 @@
+<svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path d="M14 3.5H2V5H14V3.5ZM8 8.811L12.939 13.75L14.001 12.689L8.531 7.219C8.238 6.926 7.763 6.926 7.47 7.219L2 12.689L3.061 13.75L8 8.811Z" fill="black"/>
+</svg>