This PR fixes two issues:
1. The prompt library window didn't set an `app_id` on Linux, which
caused it to be missing the Zed logo
2. A dangling reference to the window in the Wayland client code, which
caused the prompt library window not to close. See:
https://github.com/zed-industries/zed/pull/13201
Release Notes:
- Linux: Fixed the prompt library not closing on Wayland
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Co-authored-by: Junkui Zhang <364772080@qq.com>