Should recognize EIP-681 links

### Describe the bug

I'm not sure whether this is a bug or the lack of an obvious feature.

### Steps to reproduce

1. click on an EIP-681 link, e.g. ethereum:0xf4BE4f05c35A82BD2369c0bFdcf3588dE07967aC@56/whatever?a=1

Expected: if I have Metamask installed, and I haven't previously configured my system to use some other wallet application to handle EIP⁻681-schema links, Metamask should pop up and offer me to do the transaction.

Observed: Metamask does nothing.

### Error messages or log output

_No response_

### Version

10.14.6

### Build type

_No response_

### Browser

Chrome

### Operating system

Linux

### Hardware wallet

_No response_

### Additional context

_No response_

Start by reproducing the reported behavior in Chrome on Linux with the example EIP-681 link and compare it with the expected MetaMask response. No source file, test, or entry point is identified in the issue, so first locate the extension's handling of external protocol links. Done means the link is recognized and MetaMask offers the transaction when no other wallet application is configured.

Written by the indexing model from the issue text.