fix: correct token/fiat toggle background (#23228)

## **Description**

Fixed token/fiat toggle background

## **Changelog**

CHANGELOG entry: Fixed token/fiat toggle background

## **Related issues**

Fixes: https://consensyssoftware.atlassian.net/browse/MDP-254

## **Manual testing steps**

```gherkin
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]
```

## **Screenshots/Recordings**

`~`

### **Before**

<img width="500" alt="Simulator Screenshot - iPhone 16 Pro Max -
2025-11-24 at 17 10 00"
src="https://github.com/user-attachments/assets/ab62b6ba-623b-4e9b-a62f-3c055da2e8c4"
/>

### **After**

<img width="500" alt="Simulator Screenshot - iPhone 16 Pro Max -
2025-11-24 at 17 10 20"
src="https://github.com/user-attachments/assets/dca102f9-d485-42d9-a326-5f65e07d8c59"
/>

## **Pre-merge author checklist**

- [x] I’ve followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I’ve included tests if applicable
- [x] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [x] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [x] 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.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Switches `currencyTag` background to `theme.colors.background.section`
to correct the token/fiat toggle appearance.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
08a15a0. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: vinnyhoward

app/components/Views/confirmations/components/send/amount/amount.styles.ts

@@ -49,7 +49,7 @@ export const styleSheet = (params: {
     },
     currencyTag: {
       alignSelf: 'center',
-      backgroundColor: theme.colors.background.alternative,
+      backgroundColor: theme.colors.background.section,
       color: theme.colors.text.alternative,
       flexDirection: FlexDirection.Row,
       justifyContent: JustifyContent.center,