fix: adds backup button click handler and navigates to backup flow (#20832)

<!--
Please submit this PR as a draft initially.
Do not mark it as "Ready for review" until the template has been
completely filled out, and PR status checks have passed at least once.
-->

## **Description**
This PR adds backup button click handler on the new account details
screen.
<!--
Write a short description of the changes included in this pull request,
also include relevant motivation and context. Have in mind the following
questions:
1. What is the reason for the change?
2. What is the improvement/solution?
-->

## **Changelog**

<!--
If this PR is not End-User-Facing and should not show up in the
CHANGELOG, you can choose to either:
1. Write `CHANGELOG entry: null`
2. Label with `no-changelog`

If this PR is End-User-Facing, please write a short User-Facing
description in the past tense like:
`CHANGELOG entry: Added a new tab for users to see their NFTs`
`CHANGELOG entry: Fixed a bug that was causing some NFTs to flicker`

(This helps the Release Engineer do their job more quickly and
accurately)
-->

CHANGELOG entry: Added a backup button click handler on new account
details screen

## **Related issues**

Fixes:
Jira ticket: https://consensyssoftware.atlassian.net/browse/MUL-877
## **Manual testing steps**

```gherkin
Feature: Backup SRP

  Scenario: user goes to manual backup SRP screen
    Given user onboarded without backup SRP

    When user navigates to account details and clicks "Backup" text on the SRP burron
    Then user is navigated to backup srp flow (first screen asks for password)
```

## **Screenshots/Recordings**

<!-- If applicable, add screenshots and/or recordings to visualize the
before and after of your change. -->

### **Before**

<!-- [screenshots/recordings] -->


https://github.com/user-attachments/assets/deb0e131-a7af-4a75-9876-0b85e86fb7df


### **After**


https://github.com/user-attachments/assets/b6ab9788-38ad-4caa-b7b3-0440ade7fe61


<!-- [screenshots/recordings] -->

## **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**

- [ ] 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.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Make the SRP backup label clickable to launch the manual backup flow
and add a test to verify navigation.
> 
> - **UI/Navigation**
> - In `SecretRecoveryPhrase.tsx`, wrap backup label in a
`TouchableOpacity` with `handleBackupPressed` to navigate to
`Routes.SET_PASSWORD_FLOW.MANUAL_BACKUP_STEP_1` with `{ backupFlow: true
}`.
>   - Preserve existing SRP reveal navigation via `onExportMnemonic`.
> - **Tests**
> - In `SecretRecoveryPhrase.test.tsx`, add test asserting backup label
press navigates to `SetPasswordFlow` → `ManualBackupStep1` with `{
backupFlow: true }`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
62d2290. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: PatrykLucka

app/components/Views/MultichainAccounts/AccountGroupDetails/components/SecretRecoveryPhrase.test.tsx

@@ -83,4 +83,21 @@ describe('SecretRecoveryPhrase', () => {
       keyringId: 'mock-entropy-source',
     });
   });
+
+  it('navigates to manual backup flow when backup button is pressed', () => {
+    const { getByText } = renderWithProvider(
+      <SecretRecoveryPhrase account={mockAccount} />,
+      { state: mockInitialState },
+    );
+
+    const backupButton = getByText(
+      strings('multichain_accounts.export_credentials.backup'),
+    );
+    fireEvent.press(backupButton);
+
+    expect(mockNavigate).toHaveBeenCalledWith('SetPasswordFlow', {
+      screen: 'ManualBackupStep1',
+      params: { backupFlow: true },
+    });
+  });
 });

app/components/Views/MultichainAccounts/AccountGroupDetails/components/SecretRecoveryPhrase.tsx

@@ -58,6 +58,13 @@ export const SecretRecoveryPhrase = ({
     }
   }, [navigation, account?.options.entropySource]);
 
+  const handleBackupPressed = useCallback(() => {
+    navigation.navigate(Routes.SET_PASSWORD_FLOW.ROOT, {
+      screen: Routes.SET_PASSWORD_FLOW.MANUAL_BACKUP_STEP_1,
+      params: { backupFlow: true },
+    });
+  }, [navigation]);
+
   return (
     <TouchableOpacity
       style={styles.secretRecoveryPhrase}
@@ -73,12 +80,14 @@ export const SecretRecoveryPhrase = ({
         gap={8}
       >
         {showSeedphraseBackReminder && (
-          <Text
-            variant={TextVariant.BodyMDMedium}
-            color={TextColor.Alternative}
-          >
-            {strings('multichain_accounts.export_credentials.backup')}
-          </Text>
+          <TouchableOpacity onPress={handleBackupPressed}>
+            <Text
+              variant={TextVariant.BodyMDMedium}
+              color={TextColor.Alternative}
+            >
+              {strings('multichain_accounts.export_credentials.backup')}
+            </Text>
+          </TouchableOpacity>
         )}
         <Icon
           name={IconName.ArrowRight}