fix: provide pdfjs WASM files for JPEG 2000 decoding in booklets

PDF booklets use JPEG 2000 images which require OpenJPEG WASM.
Copy pdfjs-dist WASM files to static/pdfjs/ so they are served
at a known URL, and set wasmUrl parameter on getDocument().

src/lib/components/BookletViewer.svelte

@@ -54,6 +54,8 @@
         data,
         disableRange: true,
         disableAutoFetch: true,
+        useWorkerFetch: false,
+        wasmUrl: '/pdfjs/',
       });
 
       pdfDoc = await loadingTask.promise;