refactor(dashboard): UI cleanup

[datfooldive]

改了什么 / What changed

The dashboard CSS was ugly so i rewrote it. Also replaced the 5 buttons per row with a three-dot menu.

为什么 / Why

It was ugly.

测试 / Testing

• Manually checked all panels on desktop (1440px), tablet (900px), mobile (640px)
• Account table three-dot menu works — opens, flips up near bottom, click outside closes
• No automated tests (project has no test suite for dashboard UI)

Checklist

• 代码风格和现有文件一致 / Code style matches existing files
• 没有引入 npm 依赖 / No new npm dependencies (project is zero-dep)
• 涉及 LS binary 协议改动时 在 PR 描述里注明字段号来源 / If touching LS protocol, document field-number source in the PR description
• 涉及 dashboard UI 用 App.confirm / App.prompt 不用浏览器原生 alert/confirm / Uses App.confirm / App.prompt, not native dialogs (if dashboard)

[datfooldive]