[Feature]: 应该运行miniapp和canvas一样可以在右侧放置，或者改善现有组件布局

### Problem / opportunity

应该运行miniapp和canvas一样可以在右侧放置，或者改善现有组件布局，目前布局（包括miniapp的启动位置只能在非设置页的左下角）和操控逻辑都比较混乱，形成一种好像功能非常多但是使用体验不佳的情况。

### Proposed behavior

这里只说canvas和miniapp的情况，miniapp作为定义上可以和会话协同的小程序，它只能通过单独页面呈现而甚至不能和会话本身并列显示和操控，canvas 做为一个展示用的权限限制的页面反而可以做到这些，但某种意义上这2个功能重复了，canvas过于弱（权限受限），miniapp 操控过于复杂（最好使用skill编程获取），但是也只是生成一个内嵌的小功能app；

### Product surface

Desktop app

### Details, examples, or constraints

功能上，bitfun已经足够丰富；交互上还是偏于麻烦

The issue names the Desktop app but no files, tests, or entry points. Start by locating the miniapp and canvas layout and control implementations, then compare how each is launched and displayed. Done would require a decided, testable interaction design that lets miniapp and canvas appear beside the conversation or clearly improves their placement and control flow.

Scritto dal modello di indicizzazione a partire dal testo della issue.