fix(perps): change fee rounding for small fees

[michalconsensys]

Description

Adds a small-fee threshold to show "< $0.01" for fees below $0.01, improving readability and avoiding misleading precision.

Changelog

CHANGELOG entry: Display < $0.01 for small fees in Perps

Related issues

Fixes: https://consensyssoftware.atlassian.net/browse/TAT-1970

Manual testing steps

Feature: Perps position transaction view fee display

  Scenario: user views transaction with small fee
    Given a user has a closed position transaction with a fee less than $0.01 (e.g., $0.005)
    When user views the transaction details screen
    Then the fee should display as "< $0.01" instead of the exact amount

Screenshots/Recordings

Before

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.

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Note

Introduces formatFee to show "< $0.01" for fees below $0.01 and updates Perps transaction views and tests to use it.

• Utilities:
  • Add formatFee in app/components/UI/Perps/utils/formatUtils.ts to return "$0", "< $0.01", or formatted fiat; add comprehensive unit tests.
• Views:
  • Replace ad-hoc fee formatting with formatFee in PerpsOrderTransactionView.tsx and PerpsPositionTransactionView.tsx; ensure unfilled orders show $0.
• Tests:
  • Update and expand tests in transaction view specs to assert "< $0.01" behavior and edge cases; keep existing explorer navigation tests intact.

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[github-actions]

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[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
1 Accepted issue

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

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