Normalize bullet glyphs in the image preparation disconnect snapshot (#45781)

Replace `◦` with `•` in the rendered popup before comparing the
`image_preparation_disconnected` snapshot.

GitOrigin-RevId: f951c5e1f230bf8ee6d7f32a41f41316feabcb0f

codex-rs/tui/src/chatwidget/tests/composer_submission.rs

@@ -2796,6 +2796,7 @@ fn image_preparation_keeps_input_responsive_and_preserves_pending_input() {
                     assert_chatwidget_snapshot!(
                         "image_preparation_disconnected",
                         normalize_snapshot_paths(render_bottom_popup(&chat, /*width*/ 80))
+                            .replace('◦', "•")
                     );
                     chat.on_images_prepared(id);
                 } else {