fix: Implement nonEVM zero balance check to send flow before onAmountInput (#38043)

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## **Description**

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This PR adds zero balance check before `onAmountInput` RPC call to
nonEVM send flow amount validations.

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## **Related issues**

Fixes: MetaMask/metamask-mobile#22812

## **Manual testing steps**

1. Go to send flow
2. Don't have any Tron / SOL / BTC
3. Try sending it but see "insufficient balance" error

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### **Before**

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### **After**

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<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Adds an early zero-balance check for non-EVM send amount validation
and covers it with a new test.
> 
> - **Validation (send)**:
> - Non-EVM: Add early zero-balance check in `useAmountValidation`
(`validateNonEvmAmount`) returning `insufficientFundsSend` before snap
RPC; include `rawBalanceNumeric` in hook deps.
> - **Tests**:
> - Add test ensuring non-EVM accounts with zero balance surface
"Insufficient funds".
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
cd0a0e6. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: OGPoyraz

ui/pages/confirmations/hooks/send/useAmountValidation.test.ts

@@ -415,4 +415,25 @@ describe('useAmountValidation', () => {
     const error = await result.current.validateNonEvmAmountAsync();
     expect(error).toEqual(undefined);
   });
+
+  it('returns error when non-EVM account has zero balance', async () => {
+    jest.spyOn(SendContext, 'useSendContext').mockReturnValue({
+      asset: {
+        isNative: true,
+        rawBalance: '0x0',
+        decimals: 18,
+      },
+      chainId: 'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp',
+      from: MOCK_ADDRESS_1,
+      value: '1',
+    } as unknown as SendContext.SendContextType);
+
+    const { result } = renderHookWithProvider(
+      () => useAmountValidation(),
+      mockState,
+    );
+    await waitFor(() =>
+      expect(result.current.amountError).toEqual('Insufficient funds'),
+    );
+  });
 });

ui/pages/confirmations/hooks/send/useAmountValidation.ts

@@ -37,6 +37,10 @@ export const useAmountValidation = () => {
       return undefined;
     }
 
+    if (rawBalanceNumeric.isZero()) {
+      return t('insufficientFundsSend');
+    }
+
     try {
       const result = (await validateAmountWithSnap(
         value || '0',
@@ -49,7 +53,7 @@ export const useAmountValidation = () => {
     } catch (error) {
       return t('invalidValue');
     }
-  }, [t, value, validateAmountWithSnap, isNonEvmSendType]);
+  }, [t, value, validateAmountWithSnap, isNonEvmSendType, rawBalanceNumeric]);
 
   const validateAmountAsync = useCallback(async () => {
     if (!value) {