feat(STX-331): replace legacy STX swaps flags with smart transaction flags from remote config API

[rarquevaux]

Description

Upgrades @metamask/smart-transactions-controller and consolidates feature flag logic by delegating to the controller's built-in selector (selectSmartTransactionsFeatureFlagsForChain).

Key changes:

• Removes local feature flag selector implementation in favor of the controller's exported selector
• Updates getSmartTransactionsFeatureFlagsForChain to wrap the controller's selector, which handles validation and merging of default + chain-specific config

This removes the usage of the smart-transactions section of the swaps feature flags. No functional changes are expected.

Dependency on MetaMask/smart-transactions-controller#550. The smart-controller-version will have to be updated.

Changelog

CHANGELOG entry: upgrade smart-transactions-controller and replace the legacy smart transactions swaps flag with smart transactions flag from remote config API.

Related issues

Fixes:

Manual testing steps

1. Go to this page...

Screenshots/Recordings

Before

After

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Extension 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.

[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.

[metamaskbot]

✨ Files requiring CODEOWNER review ✨

✅ @MetaMask/confirmations (2 files, +28 -16)

• 📁 ui/
  • 📁 pages/
    • 📁 confirmations/
      • 📁 hooks/
        • 📄 useSmartTransactionFeatureFlags.test.ts +18 -15
        • 📄 useSmartTransactionFeatureFlags.ts +10 -1

---

💸 @MetaMask/transactions (4 files, +74 -156)

• 📁 app/
  • 📁 scripts/
    • 📁 controller-init/
      • 📁 smart-transactions/
        • 📄 smart-transactions-controller-init.test.ts +1 -62
        • 📄 smart-transactions-controller-init.ts +2 -14
    • 📁 lib/
      • 📁 smart-transaction/
        • 📄 smart-transactions.test.ts +57 -50
        • 📄 smart-transactions.ts +14 -30

[rarquevaux]

I kept this for now and the setSwapsFeatureFlags dispatch cause I am not sure if it is read at some point in the codebase

[rarquevaux]

@dan437 , do we still have a use case for this?