Refresh animated terminal titles without redrawing the TUI (#40618)

## Why

Terminal title animations only need to update the title, but each animation tick
previously requested a full TUI frame.

## What changed

- Track the next terminal title refresh deadline on `ChatWidget`.
- Have the foreground event loop refresh the title when that deadline expires.
- Clear the deadline when title animations are disabled or the configured title is
  empty.

## Testing

- Verify spinner and action-required animations set the expected refresh deadlines.
- Verify refreshing an animated title does not enqueue a TUI draw request.

GitOrigin-RevId: 269347cd48de4ad9ba9a0aef9ed105c25d1a7dae

codex-rs/tui/src/chatwidget.rs

@@ -740,6 +740,8 @@ pub(crate) struct ChatWidget {
     terminal_title_setup_original_items: Option<Option<Vec<String>>>,
     // Baseline instant used to animate spinner-prefixed title statuses.
     terminal_title_animation_origin: Instant,
+    // The foreground loop refreshes the title at this deadline without drawing a frame.
+    pub(crate) terminal_title_next_refresh: Option<Instant>,
     // Cached project-root display name keyed by cwd for status/title rendering.
     status_line_project_root_name_cache: Option<CachedProjectRootName>,
     // Cached git branch name for the status line (None if unknown).