Add a searchable /config preferences panel to the TUI (#52990)

## What changed

- Group preferences into Appearance, Notifications, Input, Sessions, and Text selection tabs, with search and links to existing theme, status line, terminal title, and keyboard editors.
- Persist preference changes to the selected local configuration file, apply supported changes immediately, and show save errors, configuration overrides, and restart requirements in the panel.
- Add a delayed notification test and controls for notification timing while preserving custom event filters.
- Add `tui.copy_on_select_clear_selection`, disabled by default, to clear transcript selection highlights only after confirmed automatic clipboard delivery.
- Keep local configuration editors usable while disconnected and prevent held activation keys or buffered input from triggering actions across editor and reconnect transitions.

## Testing

Add regression tests and rendering snapshots for panel navigation, search, dependency states, editor handoffs, offline persistence, notification timers, custom filter preservation, and confirmed-copy deselection.

GitOrigin-RevId: a16d218046060fcb6e61705a803fcd9297266e6e

codex-rs/thread-manager-sample/src/main.rs

@@ -295,6 +295,7 @@ async fn new_config(
         tui_fullscreen_transcript: false,
         tui_mouse_scroll_speed: None,
         tui_copy_on_select: Default::default(),
+        tui_copy_on_select_clear_selection: false,
         tui_right_click_paste: Default::default(),
         tui_alternate_screen: AltScreenMode::Auto,
         tui_status_line: None,