chore: switch to mobile optin endpoint

[sophieqgu]

Description

Changelog

CHANGELOG entry:

Related issues

Fixes:

Manual testing steps

Feature: my feature name

  Scenario: user [verb for user action]
    Given [describe expected initial app state]

    When user [verb for user action]
    Then [describe expected outcome]

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After

Pre-merge author checklist

• I’ve followed MetaMask Contributor Docs and MetaMask Mobile Coding Standards.
• I've completed the PR template to the best of my ability
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

---

Note

Migrates opt-in to a mobile timestamp-signed flow (EVM and Solana), adds InvalidTimestamp retry, and updates service endpoints, types, messenger, and tests.

• Rewards opt-in flow:
  • Replace challenge-based optin with timestamp-signed mobile flow in RewardsController using #signRewardsMessage and RewardsDataService:mobileOptin.
  • Add retry on InvalidTimestampError and support both EVM and Solana signing paths.
• Data service:
  • Add mobileOptin(body) calling /auth/mobile-optin; remove generateChallenge/optin usage for controller path.
  • Return InvalidTimestampError with server timestamp; log error payloads.
• Types:
  • Remove GenerateChallengeDto, ChallengeResponseDto, LoginDto; add MobileOptinDto and refine MobileLoginDto.
• Messenger:
  • Replace allowed actions generateChallenge/optin with mobileOptin.
• Tests:
  • Update controller and service tests for mobile opt-in (EVM/Solana), timestamp retry, and token storage handling.
  • Minor fix: cast base58.decode Buffer to Uint8Array in tests.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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The base branch was changed.