fix(rewards): remove sign for rebalance events (#29802)

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## **Description**
https://consensyssoftware.atlassian.net/browse/RWDS-1264
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## **Related issues**

Fixes:

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<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Low risk UI formatting change limited to `OndoActivityRow` display
logic, with added test coverage; no business logic, persistence, or
security-sensitive code impacted.
> 
> **Overview**
> Updates Ondo campaign activity rows so **`REBALANCE` entries display
USD amounts without the leading `+` sign**, while
deposits/withdrawals/outflows continue to use signed USD formatting.
> 
> Adds a small helper (`formatActivityUsd`) to special-case rebalance
values (returning `—` for `null`/non-numeric inputs) and extends the
unit test suite to assert the new rebalance formatting behavior.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
0ea01cd. Bugbot is set up for automated
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<!-- /CURSOR_SUMMARY -->

Author: sophieqgu

app/components/UI/Rewards/components/Campaigns/OndoActivityRow.test.tsx

@@ -104,6 +104,18 @@ describe('OndoActivityRow', () => {
     expect(getByText('—')).toBeDefined();
   });
 
+  it('renders rebalance entry USD without a plus sign for positive amounts', () => {
+    const { getByText } = render(
+      <OndoActivityRow
+        entry={createEntry({ type: 'REBALANCE', usdAmount: '5000.000000' })}
+      />,
+    );
+
+    expect(getByText('Rebalance')).toBeDefined();
+    // formatUsd (rebalance) has no '+'; deposit/withdraw still use mocked formatSignedUsd
+    expect(getByText(/^\$5,000/)).toBeDefined();
+  });
+
   it('renders external outflow entry with shortened destAddress', () => {
     const { getByText } = render(
       <OndoActivityRow

app/components/UI/Rewards/components/Campaigns/OndoActivityRow.tsx

@@ -29,6 +29,7 @@ import {
   formatRewardsDate,
   formatRewardsTimeOnly,
   formatSignedUsd,
+  formatUsd,
   getChainHex,
   shortenAddress,
 } from '../../utils/formatUtils';
@@ -51,6 +52,24 @@ const LABEL_KEY_MAP: Record<ActivityEntryType, string> = {
 const tokenLabel = (token: ActivityTokenDto): string =>
   token.tokenSymbol || token.tokenName;
 
+/** Rebalance USD is not portfolio P&L; omit the '+' used for signed inflows/outflows. */
+const formatActivityUsd = (
+  usdAmount: OndoGmActivityEntryDto['usdAmount'],
+  entryType: ActivityEntryType,
+): string => {
+  if (entryType !== 'REBALANCE') {
+    return formatSignedUsd(usdAmount);
+  }
+  if (usdAmount === null) {
+    return '—';
+  }
+  const num = typeof usdAmount === 'number' ? usdAmount : parseFloat(usdAmount);
+  if (Number.isNaN(num)) {
+    return '—';
+  }
+  return formatUsd(usdAmount);
+};
+
 interface OndoActivityRowProps {
   entry: OndoGmActivityEntryDto;
   timeOnly?: boolean;
@@ -123,7 +142,7 @@ const OndoActivityRow: React.FC<OndoActivityRowProps> = ({
             {label}
           </Text>
           <Text variant={TextVariant.BodyMd} fontWeight={FontWeight.Medium}>
-            {formatSignedUsd(entry.usdAmount)}
+            {formatActivityUsd(entry.usdAmount, entryType)}
           </Text>
         </Box>