screen goes black when the TUI app is in a background tab with iTerm2 inline image

[aome510]

Environment

• ratatui-image 11.0.6, ratatui 0.30.2
• Terminal: iTerm2
• macOS (Darwin 25.5), iTerm2 version: Build 3.6.11
• Rendering via the static Image + Picker::new_protocol(...) path (not StatefulImage)

Summary

When rendering a cover image with the iTerm2 protocol, the image displays correctly as long as the window stays focused. If the iTerm2 window/tab is moved to a background tab, after some time (often a few minutes) the inline image disappears and the affected region degrades into a black/garbled box that the app never repairs on its own

Steps to reproduce

1. Render a cover image each frame in a normal ratatui draw loop using Image::new(&protocol)
2. Run in iTerm2.
3. Cover the iTerm2 window with another app (or switch to a different tab) and leave it for a few minutes.
4. Bring it back to the foreground.

Expected: TUI looks normal.
Actual: TUI's screen goes black and no redraw restores it.