Describe the bug

Due to the change from #6376, now goose desktop bind the iframe width with the inner app width through ui/notifications/size-changed. However, ui/notifications/size-changed will only get triggered when there is not enough space in the app which cause the problem that once the app gets compressed it never grows back - see the screen recording.

P.S. I don't really know what would be the use case for the host to do something meaningful by using this size-change info from the app. Please enlighten me if anyone thinks of one. 😁

To Reproduce
Steps to reproduce the behavior:

1. Resize the goose desktop to compress the mcp app
2. Resize the goose desktop back to larger window width
3. Mcp app remains its compressed width

Expected behavior
I think the app should utilize the full width of its container.

Screenshots

Please provide the following information

• OS & Arch: macOS M3 pro
• Interface: UI
• Version: debug mode with 5bffc1c
• Provider & Model: Google – gemini-3-pro-preview