v2026.811.4

操作体验：对话中的每个代码块新增一键复制按钮（悬停显现，复制成功/失败有即时反馈）

Interaction: every code block in chat now has a one-click copy button (reveals on hover, with instant copied/failed feedback)

已通过静默安装 E2E + CDP 真机验证（代码块与复制按钮 1:1、零 renderer 异常）。/ Verified via silent-install E2E + CDP on the real app.