Release version 0.21.3

• feat(chat): Frosted message surfaces over your background image. With a workspace background image on, the surfaces inside chat messages — bubbles, capsules, cards, code headers, tables, and inline code — turn to one family of translucent frosted panels so the image shows through. Inline code also reads as a pill and tables as rounded, bordered cards.
• fix(tabs): The new-conversation button sits neatly beside the tabs. It shares the tab row and stays right next to the last tab, and over a background image its hover frost and the strip's bottom border render cleanly.

发布版本 0.21.3

• 功能(聊天)：背景图之上的磨砂消息表面。 启用工作区背景图后，消息内的各类表面——气泡、胶囊、卡片、代码标题栏、表格与内联代码——统一为一族半透明磨砂面板，背景图得以透出。内联代码也呈现为胶囊，表格呈现为带边框的圆角卡片。
• 修复(标签栏)：新建会话按钮妥帖地落在标签旁边。 按钮与标签同处一行、紧贴最后一个标签，在背景图之上其悬停磨砂与标签条底边框也渲染得干净利落。