Enhance model picker (#7709)

# External (non-OpenAI) Pull Request Requirements

Before opening this Pull Request, please read the dedicated
"Contributing" markdown file or your PR may be closed:
https://github.com/openai/codex/blob/main/docs/contributing.md

If your PR conforms to our contribution guidelines, replace this text
with a detailed and high quality description of your changes.

Include a link to a bug report or enhancement request.

codex-rs/tui/src/app_event.rs

@@ -74,6 +74,11 @@ pub(crate) enum AppEvent {
         model: ModelPreset,
     },
 
+    /// Open the full model picker (non-auto models).
+    OpenAllModelsPopup {
+        models: Vec<ModelPreset>,
+    },
+
     /// Open the confirmation prompt before enabling full access mode.
     OpenFullAccessConfirmation {
         preset: ApprovalPreset,