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/toolbarButton-editorFreeText.svg

@@ -0,0 +1,5 @@
+<svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path fill-rule="evenodd" clip-rule="evenodd" d="M3 2.5C2.72421 2.5 2.5 2.72421 2.5 3V4.75H1V3C1 1.89579 1.89579 1 3 1H13C14.1042 1 15 1.89579 15 3V4.75H13.5V3C13.5 2.72421 13.2758 2.5 13 2.5H3Z" fill="black"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M11 15H5V13.5H11V15Z" fill="black"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M8.75 2.25V14.25H7.25V2.25H8.75Z" fill="black"/>
+</svg>