<issue_title>[BUG] Coinbase Notification Type Detection, Spend Permission Grant, and Passkey Sign-In Failure</issue_title>

[joe10832]

<issue_title>[BUG] Coinbase Notification Type Detection, Spend Permission Grant, and Passkey Sign-In Failure</issue_title>
<issue_description>## Bug Description
Coinbase Notification Type Detection Logic, Spend Permission Grant, and Hardcoded Passkey Credential sign-in are not functioning as expected in Onchain Test Kit (OTK-30).

Steps to Reproduce
Prepare Onchain Test Kit and configure for Coinbase Wallet usage
Initiate a workflow that triggers notification type detection
Attempt to grant spend permission using hardcoded passkey
Try to sign in with hardcoded passkey credential
Expected Behavior
Notification type should be detected correctly, spend permission should be granted, and sign in with hardcoded passkey should succeed without errors.

Actual Behavior
Notification type is not detected; spend permission cannot be granted; sign in with hardcoded passkey credential fails. Observed error during workflow execution.

Environment Information
Onchain Test Kit Version: [please supply]
Node.js Version: [please supply]
Operating System: [please supply]
Browser: [please supply]
Wallet: Coinbase Wallet
Configuration Used
// Paste your configuration code here
// Example:
const config = configure()
.withCoinbaseWallet()
// ... other configuration for notification type and passkey
.build();
Error Logs
Error encountered during notification detection and passkey sign-in (see linked PR review).
Originally posted by @joe10832 in #197 (review)
Code Sample
import { createOnchainTest, configure } from '@coinbase/onchaintestkit';

const test = createOnchainTest(/* your config */);

test('coinbase notification test', async ({ page, coinbase }) => {
// Steps that cause the bug
});
Screenshots
N/A

Additional Context
Issue discovered while implementing OTK-30. Test failure relates to Coinbase-specific logic for notification, spend permission, and passkey credential sign-in.

Possible Solution
Review and correct the Coinbase notification detection logic, permission grant flow, and passkey credential handling in OTK.

Checklist
I have searched for existing issues that describe this bug
I have included all the required environment information
I have provided a minimal code example that reproduces the issue
I have included relevant error messages and logs
</issue_description>
<agent_instructions>import { createOnchainTest, configure } from '@coinbase/onchaintestkit';

const test = createOnchainTest(/* your config */);

test('coinbase notification test', async ({ page, coinbase }) => {
// Steps that cause the bug
});</agent_instructions>@joe10832

Originally posted by @joe10832 in #198 (comment)