Update PDF viewer to display user-uploaded documents as slides

Integrates the react-pdf library to render PDF documents page by page as slides, replacing the previous canvas-based rendering approach. Includes necessary setup for the PDF worker and static file serving.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 9a264234-c5d7-4dcc-adf3-a954b149b30d
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/3df548ff-50ae-432f-9be4-25d34eccc983/9a264234-c5d7-4dcc-adf3-a954b149b30d/VGhYqEL

server/index.ts

@@ -53,6 +53,9 @@ app.use((req, res, next) => {
 
   // Serve attached assets statically
   app.use('/attached_assets', express.static('attached_assets'));
+  
+  // Serve public folder for PDF worker and other static files
+  app.use(express.static('public'));
 
   app.use((err: any, _req: Request, res: Response, _next: NextFunction) => {
     const status = err.status || err.statusCode || 500;