feat: add isSmartWalletSignature parameter to signTypedData

[devin-ai-integration]

Description

Adds support for the isSmartWalletSignature parameter in the SDK's signTypedData method to allow users to get smart wallet signatures instead of the default signer signatures. Previously, this parameter was hardcoded to false, but the backend API already supports it.

Changes made:

• Added optional isSmartWalletSignature?: boolean parameter to SignTypedDataInput interface
• Updated EVMWallet.signTypedData method to use the parameter instead of hardcoding false
• Parameter defaults to false for backward compatibility

Context: This addresses Linear ticket WAL-6377 where users needed to get ERC6492-wrapped smart wallet signatures for permit2 compatibility testing.

Link to Devin run: https://app.devin.ai/sessions/894691ae61ac40ddaf6cce140226d50b
Requested by: @jorge2393

Test plan

⚠️ Testing limitation: This PR was not end-to-end tested due to environment constraints. Manual testing should verify:

• Backward compatibility: Existing signTypedData calls continue to work unchanged (default behavior preserved)
• New functionality: Setting isSmartWalletSignature: true returns smart wallet signatures (ERC6492-wrapped)
• Parameter passing: The parameter correctly flows through to the backend API
• Type safety: TypeScript compilation and interface compatibility confirmed ✅

Package updates

No package updates required - this is a feature addition using existing dependencies.

Human review checklist

🔍 Critical items to verify:

• Backend API actually handles isSmartWalletSignature parameter correctly
• Smart wallet signatures vs signer signatures produce different results when parameter is toggled
• No breaking changes to existing signTypedData usage
• Default value logic works as expected (false when parameter omitted)

[devin-ai-integration]

Original prompt from jorge@paella.dev

SYSTEM:
=== BEGIN THREAD HISTORY (in #help-wallets) ===
Jorge (U0757E01YJV): Trying to use <https://docs.crossmint.com/wallets/guides/sign-message-evm#signing-typed-data|signTypedData> always default to the wallet's signer, devin says `isSmartWalletSignature` is hardcoded to false. Is there a way to get a smart wallet signature?

trying to test if our sw signatures are compatible with permit2 (they should be but testing e2e to confirm)

Linear Asks (U064YQRSWJC): Jorge Villamil created a new General Ask WAL-6377 Get smart wallet signature instead of default wallet signer

*Jorge Villamil* created a new General Ask

<https://linear.app/crossmint/issue/WAL-6377/get-smart-wallet-signature-instead-of-default-wallet-signer|WAL-6377 Get smart wallet signature instead of default wallet signer>
Trying to use <https://docs.crossmint.com/wallets/guides/sign-message-evm#signing-typed-data|signTypedData> always default to the wallet's signer, devin says it's hardcoded. Is there a way to get a smart wallet signature
:slack: Synced with Slack
<https://linear.app/crossmint/team/WAL/all|[ENG] Wallets> | <!date^1756488187^{date_short_pretty} {time}|August 29, 2025>


Jorge (U0757E01YJV): @Devin trying to use signTypedData on the wallets sdk always return a signature from the signer of the wallet, figure out if it's possible to pass a isSmartWallet: true via the sdk to get a smart wallet signature

if not propose a PR to enable this
=== END THREAD HISTORY ===

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Latest commit: 81ddb54

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[devin-ai-integration]

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1 Skipped Deployment

Project	Deployment	Preview	Comments	Updated (UTC)
smart-wallet-auth-demo	Ignored			Sep 1, 2025 0:04am