fix: MUSD-181 prevent dedupliation of transactions with the 0x0 hash (MetaMask#24289)

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## **Description**
This fix prevents filtering of transactions with the "0x0" hash in the
activity view.

### Reason for change
mUSD conversions were being filtered out and hidden on the activity view
since they all have the 0x0 hash.

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## **Changelog**

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CHANGELOG entry: prevent filtering of transactions with 0x0 hash in
activity view

## **Related issues**

Fixes: [MUSD-181: MUSD conversions aren't appearing in activity
list](https://consensyssoftware.atlassian.net/browse/MUSD-181)

## **Manual testing steps**

```gherkin
Feature: Transaction history preserves distinct outgoing transactions with placeholder hashes

  Scenario: user views transaction history with multiple outgoing transactions that have a placeholder hash
    Given user has multiple outgoing transactions recorded in activity with a placeholder hash value ("0x0")

    When user opens the activity / transaction history list
    Then each of those outgoing transactions is displayed as a separate entry
```

## **Screenshots/Recordings**

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

### **Before**

<!-- [screenshots/recordings] -->
Single mUSD Conversion shown in activity list despite user performing
multiple conversions
<img width="505" height="1012" alt="image"
src="https://github.com/user-attachments/assets/430583c3-af24-407c-91f2-dbef62b52e93"
/>

### **After**

<!-- [screenshots/recordings] -->
All mUSD Conversions displayed in activity list
<img width="505" height="1012" alt="image"
src="https://github.com/user-attachments/assets/f027d5f8-9153-4c26-8923-741c575f0de7"
/>

## **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]
> Prevents unintended filtering of transactions that use the placeholder
hash `0x0`.
> 
> - Updates `filterDuplicateOutgoingTransactions` to treat `hash ===
'0x0'` as absent so these entries are never deduped
> - Adds a unit test in `utils.test.ts` verifying transactions with
`0x0` hash are preserved
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
3969d65. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: Matt561

app/components/UI/Transactions/utils.test.ts

@@ -192,5 +192,17 @@ describe('filterDuplicateOutgoingTransactions', () => {
       expect(result).toHaveLength(1);
       expect(result[0].id).toBe('3');
     });
+
+    it("preserves transactions when hash is placeholder '0x0'", () => {
+      const PLACEHOLDER_HASH = '0x0';
+      const transactions = [
+        createTransaction('1', 'musdConversion', PLACEHOLDER_HASH, '100'),
+        createTransaction('2', 'musdConversion', PLACEHOLDER_HASH, '100'),
+      ];
+
+      const result = filterDuplicateOutgoingTransactions(transactions);
+
+      expect(result).toEqual(transactions);
+    });
   });
 });

app/components/UI/Transactions/utils.ts

@@ -15,7 +15,9 @@ export const filterDuplicateOutgoingTransactions = (
   }
 
   return transactions.filter((currentTx, currentIndex) => {
-    if (!currentTx.hash) {
+    // Treat placeholder hash ('0x0') as "no hash" to avoid deduping unrelated tx metas
+    // (e.g., MetaMask Pay intent/wrapper transactions that never receive a real tx hash).
+    if (!currentTx.hash || currentTx.hash === '0x0') {
       return true; // Keep transactions without a hash
     }