fix: prevent gain/loss sign from wrapping off the amount (#158)

The `+`/`-` sign and the formatted amount are separate text nodes inside
the same `<span>`, allowing the browser to break between them when
horizontal space is tight — leaving the sign orphaned on a separate
line.

## Changes

- **`account-balance-chart.tsx`, `account-list-card.tsx`,
`account-balance-card.tsx`**: Added `whitespace-nowrap` to the gain/loss
amount `<span>` in all three components

```diff
- className={`text-right font-mono tabular-nums ${...}`}
+ className={`whitespace-nowrap text-right font-mono tabular-nums ${...}`}
```

<!-- START COPILOT ORIGINAL PROMPT -->



<details>

<summary>Original prompt</summary>

> 
> ----
> 
> *This section details on the original issue you should resolve*
> 
> <issue_title>The gain/lost amount is broken in two lines by the symbol
when there is no enough space</issue_title>
>
<issue_description>![ResizedImage_2026-02-25_18-12-15_5005.png](https://github.com/user-attachments/assets/70285291-ceca-4116-ad05-df8e97007e41)
> 
> </issue_description>
> 
> ## Comments on the Issue (you are @copilot in this section)
> 
> <comments>
> </comments>
> 


</details>



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- Fixes whisper-money/whisper-money#157

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: victor-falcon <238766+victor-falcon@users.noreply.github.com>

resources/js/components/accounts/account-balance-chart.tsx

@@ -106,7 +106,7 @@ function InvestmentTooltipContent({
                                 {__('Gain/loss')}
                             </span>
                             <span
-                                className={`font-mono font-medium tabular-nums ${gain >= 0 ? 'text-green-600 dark:text-green-400' : 'text-red-600 dark:text-red-400'}`}
+                                className={`whitespace-nowrap font-mono font-medium tabular-nums ${gain >= 0 ? 'text-green-600 dark:text-green-400' : 'text-red-600 dark:text-red-400'}`}
                             >
                                 {gain >= 0 ? '+' : ''}
                                 {valueFormatter(gain)}

resources/js/components/accounts/account-list-card.tsx

@@ -176,7 +176,7 @@ export function AccountListCard({
                                                                     )}
                                                                 </span>
                                                                 <span
-                                                                    className={`text-right font-mono tabular-nums ${gain >= 0 ? 'text-green-600 dark:text-green-400' : 'text-red-600 dark:text-red-400'}`}
+                                                                    className={`whitespace-nowrap text-right font-mono tabular-nums ${gain >= 0 ? 'text-green-600 dark:text-green-400' : 'text-red-600 dark:text-red-400'}`}
                                                                 >
                                                                     {gain >= 0
                                                                         ? '+'

resources/js/components/dashboard/account-balance-card.tsx

@@ -161,7 +161,7 @@ export function AccountBalanceCard({
                                                                     )}
                                                                 </span>
                                                                 <span
-                                                                    className={`text-right font-mono tabular-nums ${gain >= 0 ? 'text-green-600 dark:text-green-400' : 'text-red-600 dark:text-red-400'}`}
+                                                                    className={`whitespace-nowrap text-right font-mono tabular-nums ${gain >= 0 ? 'text-green-600 dark:text-green-400' : 'text-red-600 dark:text-red-400'}`}
                                                                 >
                                                                     {gain >= 0
                                                                         ? '+'