Model selector dropdown extends off-screen on smaller displays, preventing access to top menu options

When opening the model selector dropdown on smaller screens, the menu opens upward and extends beyond the top of the viewport, making the top options completely inaccessible. The dropdown does not provide internal scrolling or intelligent positioning to account for limited space.

Specifically, on an iPad used as a secondary display with Chrome open (viewport: 1072 x 590 px), trying to access the model selector reveals only the bottom portion of the menu.  Options like "Retry with same model" are rendered off-screen above the visible area, and there is no way to scroll within the dropdown to reach them.

Steps to Reproduce:

1. Open interface on a display with limited resolution (e.g., 1072 x 590 px viewport)

2. Click the model selector dropdown at the bottom of the chat interface

3. Observe that only the bottom menu options are visible

4. Attempt to access or scroll to top menu options