Function createBatchedSignaturePrompter

createBatchedSignaturePrompter(): SignaturePrompter
Batched signature prompter that captures user gesture once for multiple signatures

This function creates a signature prompter that shows a modal only on the first signature request, informing the user that multiple signatures are required. After the user clicks "Continue" on the initial modal, subsequent signature requests bypass the modal and proceed directly to the wallet.

This solves the poor UX of requiring three separate user gestures for file upload, which involves three signatures: layout, index, and auth.

The prompter:
1. On first signature request (layout): Shows a modal explaining three signatures are needed
2. Waits for user to click "Continue" (this grants the user gesture)
3. Sets an internal flag to bypass the modal for subsequent signatures
4. Subsequent signatures (index, auth) proceed directly without showing the modal
Returns SignaturePrompter
A SignaturePrompter function with batched gesture handling
Example
```
const uploader = new CascadeUploader(...);

await uploader.uploadFile(fileBytes, {
  fileName: 'example.txt',
  expirationTime: '...',
  signaturePrompter: createBatchedSignaturePrompter()
});
```
- Defined in src/wallets/prompter.ts:393