[Delegation Toolkit] Adds tutorial

[AyushBherwani1998]

Description

Adds a new tutorial: Use passkey as backup signer

Issue(s) fixed

Fixes #2210

Preview

https://metamask-docs-7w1b20o5s-consensys-ddffed67.vercel.app/delegation-toolkit/development/tutorials/use-passkey-as-backup-signer/

Checklist

Complete this checklist before merging your PR:

• If this PR contains a major change to the documentation content, I have added an entry to the top of the "What's new?" page.
• The proposed changes have been reviewed and approved by a member of the documentation team.

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Project	Deployment	Preview	Comments	Updated (UTC)
metamask-docs	Ready	Preview	Comment	Aug 27, 2025 8:02pm

[alexandratran]

I edited the tutorial for clarity and also made edits to other signing content for clarity and consistency.

I just have one main question: In the tutorial, we assume that user has already created and deployed a smart account as a prerequisite, but we also include a step to create a smart account. Should we either remove it from the prerequisites or remove it as a step?

[AyushBherwani1998]

In the tutorial, we assume that user has already created and deployed a smart account as a prerequisite, but we also include a step to create a smart account. Should we either remove it from the prerequisites or remove it as a step?

It's correct, so prerequisite is creating and deploying a smart account, where as in step 3, we are again accessing the same account so we can register the passkey. As the call data needs to be signed by the smart account, and sent to smart account address, that step is required.

[bgravenorst]

lgtm