修复：StatCard 数值溢出问题

[wucm667]

• 添加 title 属性，鼠标悬停时显示完整数值
• 添加 truncate 类防止数值溢出
• 优化长数值的显示效果
  

[Copilot]

Pull request overview

该 PR 旨在修复 StatCard 在展示超长数值时的溢出问题，通过在 UI 上截断显示并提供悬停查看完整值的方式改善可读性。

Changes:

• 为 .stat-value 增加 truncate 样式，避免长数值撑破布局
• 在 StatCard 的数值元素上增加 title 属性，支持 hover 显示完整内容

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
frontend/src/style.css	给统计卡片数值样式增加 truncate 以减少溢出
frontend/src/components/common/StatCard.vue	给数值增加 title tooltip 展示完整值

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[Copilot]

truncate alone often won’t actually ellipsize inside a flex row because flex items default to min-width: auto (can’t shrink below content). Since .stat-value is rendered as a flex item next to the trend <span>, long values may still overflow instead of truncating. Consider adding min-w-0 (and optionally flex-1 / max-w-full) to .stat-value or to the flex container’s children so truncation reliably works.

Suggested change

	@apply text-2xl font-bold text-gray-900 dark:text-white truncate;
	@apply text-2xl font-bold text-gray-900 dark:text-white truncate min-w-0 max-w-full;