fix: 优化 Toast 样式使其更明显

- 增大字体从 16px 到 18px
- 添加字重加粗 (font-semibold)
- 增加内边距 (px: 12→24, py: 8→16)
- 增加外边距 (mx: 20→40)
- 增加背景不透明度 (85%→90%)
- 增加圆角 (2px→8px)
- 添加阴影效果 (shadow-lg)
- 调整垂直位置 (mt-[-40px]→mt-[-80px])

Co-Authored-By: Claude <noreply@anthropic.com>

components/ui/Toast.tsx

@@ -73,12 +73,12 @@ const Toast = (function () {
       if (renderContent) {
         return renderContent()
       }
-      return title && <Text className="text-[16px] text-white">{title}</Text>
+      return title && <Text className="text-[18px] font-semibold text-white">{title}</Text>
     }
 
       ; (global as any).toast?.show(
         <Block className="z-[9999] flex items-center justify-center">
-          <Block className="relative mx-[20px] mt-[-40px] rounded-[2px] bg-black/85 px-[12px] py-[8px]">
+          <Block className="relative mx-[40px] mt-[-80px] rounded-[8px] bg-black/90 px-[24px] py-[16px] shadow-lg">
             {renderBody()}
           </Block>
         </Block>,