refactor(toast): migrate earn toasts to the design system

[amandaye0h]

Description

Earn still showed notifications through the legacy ToastContext showToast API. This PR switches useEarnToasts to the design-system toast() API so Earn flows share the same toaster as the rest of the toast migration.

Copy now maps to title / description, success and error use ToastSeverity icons, and in-progress still uses the spinner accessory. Close is handled by the design-system toaster. The Money toast migration lives on migrate/use-money-toasts.

Changelog

CHANGELOG entry: null

Related issues

Fixes:

Refs: No tracking issue; continues the design-system toast migration for Earn flows

Manual testing steps

Feature: Earn design-system toasts

  Background:
    Given I am logged into MetaMask Mobile

  Scenario: user sees an Earn mUSD conversion toast
    Given I can convert a token to mUSD

    When user confirms an mUSD conversion
    Then an in-progress toast appears with a spinner
    And a success or failure toast replaces it when the transaction settles
    And the toast can be dismissed with the design-system close control

Screenshots/Recordings

Before

N/A

After

N/A

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.

Performance checks (if applicable)

• I've tested on Android
  • Ideally on a mid-range device; emulator is acceptable
• I've tested with a power user scenario
  • Use these power-user SRPs to import wallets with many accounts and tokens
• I've instrumented key operations with Sentry traces for production performance metrics
  • See trace() for usage and addToken for an example

For performance guidelines and tooling, see the Performance Guide.

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.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[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

See analysis details on SonarQube Cloud