clean models manager (#9168)

Have only the following Methods:
- `list_models`: getting current available models
- `try_list_models`: sync version no refresh for tui use
- `get_default_model`: get the default model (should be tightened to
core and received on session configuration)
- `get_model_info`: get `ModelInfo` for a specific model (should be
tightened to core but used in tests)
- `refresh_if_new_etag`: trigger refresh on different etags

Also move the cache to its own struct

codex-rs/tui2/src/app.rs

@@ -50,6 +50,7 @@ use codex_core::config::edit::ConfigEditsBuilder;
 #[cfg(target_os = "windows")]
 use codex_core::features::Feature;
 use codex_core::models_manager::manager::ModelsManager;
+use codex_core::models_manager::manager::RefreshStrategy;
 use codex_core::models_manager::model_presets::HIDE_GPT_5_1_CODEX_MAX_MIGRATION_PROMPT_CONFIG;
 use codex_core::models_manager::model_presets::HIDE_GPT5_1_MIGRATION_PROMPT_CONFIG;
 use codex_core::protocol::DeprecationNoticeEvent;
@@ -249,7 +250,9 @@ async fn handle_model_migration_prompt_if_needed(
     app_event_tx: &AppEventSender,
     models_manager: Arc<ModelsManager>,
 ) -> Option<AppExitInfo> {
-    let available_models = models_manager.list_models(config).await;
+    let available_models = models_manager
+        .list_models(config, RefreshStrategy::OnlineIfUncached)
+        .await;
     let upgrade = available_models
         .iter()
         .find(|preset| preset.model == model)
@@ -451,7 +454,7 @@ impl App {
         ));
         let mut model = thread_manager
             .get_models_manager()
-            .get_model(&config.model, &config)
+            .get_default_model(&config.model, &config, RefreshStrategy::OnlineIfUncached)
             .await;
         let exit_info = handle_model_migration_prompt_if_needed(
             tui,