fix: await sealMessage which is now async

[avral]

Summary

sealMessage from @wharfkit/protocol-esr is now an async function, but it was being called without await. This caused the Promise object to be serialized as an empty object {}, resulting in an empty message being sent to the Buoy callback service.

Error: POST https://cb.anchor.link/... 400 (Bad Request) with body "Unable to forward empty message"

Root Cause

In @wharfkit/protocol-esr v1.6.0, sealMessage is defined as:

async function sealMessage(message, privateKey, publicKey, nonce) {
    return sealedMessagePayload(message, privateKey, publicKey, nonce);
}

But in this plugin it was called without await:

const sealedMessage = sealMessage(...) // Returns Promise, not SealedMessage

When Serializer.encode({ object: sealedMessage }) is called on a Promise, it produces an empty byte array.

Fix

- const sealedMessage = sealMessage(...)
+ const sealedMessage = await sealMessage(...)

Test Plan

• Tested transaction signing with WebAuth wallet after fix
• Verified sealed message is properly encoded (63+ bytes vs 0 bytes before)

🤖 Generated with Claude Code

[andreyjamer]

Hello! Thank you for the PR. Yes it is caused by @wharfkit/protocol-esr update. In version 1.4.0 this method didn't return Promise.
Anyway I created another PR with your change + I bumped versions of our 3rdparty deps. #13

It should be reviewed and released soon

[andreyjamer]

@avral New version of @proton/wharfkit-plugin-webauth released. It already has this change. Feel free to update and try.
I'll close this PR for now.