ERC-4361 / Sign-In with Ethereum (SIWE) User Interface Support

**Describe the usability problem**
(Please provide a reference and close this issue if this has already been raised. I searched issues and PRs and didn't find any mention.)

As of writing, providing an ERC-4361 message for personal sign in Metamask Mobile only shows the usual message signing screen. It will be much better for mobile users to see a similar sign-in screen as the desktop version of Metamask for increased confidence.

**Screenshots**
https://docs.metamask.io/wallet/how-to/sign-data/siwe/

**Proposed behavior**
Show a similar sign-in screen in the mobile version of Metamask when an ERC-4361 message is provided for signing.

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**User impact | Usage frequency | Feasibility scores**
_How important is this to the user, what the user wants to accomplish | Daily, weekly, monthly | Small, medium, large_

Start by reviewing the existing mobile personal-message signing flow and compare it with the desktop Sign-In with Ethereum experience referenced in the issue. Use the linked MetaMask SIWE documentation and determine how ERC-4361 messages are identified. Done means an ERC-4361 signing request presents a dedicated sign-in screen in the mobile app rather than the usual message-signing screen.

Written by the indexing model from the issue text.