图例文字较长时文字被截断

### 问题描述

如图所示，图例文字较长时，字会被截断，展示不全。

任意图例名称较长时可复现，例如 'order_count', 'total_sales'，可复现 spec 如下
```
chart.options({
type: 'interval',
data: [
{name: 'total_sales', month: 'May', number: 10},
{name: 'total_sales', month: 'Apr', number: 20},
{name: 'order_count', month: 'May', number: 20},
{name: 'order_count', month: 'Apr', number: 30}
],
encode: {
x: 'month',
y: 'number',
color: 'name'
},
transform: [{ type: 'stackY' }]
})
```

### 重现链接

_No response_

### 重现步骤

_No response_

### 预期行为

期望能完整展示

### 平台

- 操作系统: [macOS, Windows, Linux, React Native ...]
- 网页浏览器: [Google Chrome, Safari, Firefox]

### 屏幕截图或视频（可选）

_No response_

### 补充说明（可选）

_No response_

Start with the provided chart.options reproduction using the interval chart, stacked data, and color legend, then trace the legend rendering path to find where long names such as “total_sales” are clipped. Done means the complete legend labels are visible for the supplied example and for other long legend names.

Written by the indexing model from the issue text.