Add independent controls for TUI visual effects (#46832)

## What changed

Replace `tui.whimsy` with `[tui.effects]` preferences for `starfield`, `shimmer`, `welcome`, `effort`, `progress`, and `title`. Each defaults to `true` and remains subordinate to the `tui.animations` master switch.

Wire the preferences into composer effects, welcome artwork, status and loading text, progress indicators, and terminal-title animations. For example, disable shimmering text while keeping progress animations:

```toml
[tui.effects]
shimmer = false
```

Keep retired `tui.whimsy` entries loadable but ignore their value. Update the configuration schema to expose the new preferences.

## Testing

Add and extend coverage for independent shimmer and progress effects, master-switch precedence, welcome and starfield controls, terminal-title blinking, and strict configuration loading with the retired setting.

GitOrigin-RevId: 28b37ba52872133b8954543cabe9ff424147f1c5

codex-rs/tui/src/onboarding/onboarding_screen.rs

@@ -136,7 +136,7 @@ impl OnboardingScreen {
         steps.push(Step::Welcome(WelcomeWidget::new(
             !matches!(login_status, LoginStatus::NotAuthenticated),
             tui.frame_requester(),
-            local_settings.tui.animations,
+            local_settings.tui.animations && local_settings.tui.effects.welcome,
         )));
         #[cfg(target_os = "windows")]
         let show_windows_create_sandbox_hint = if show_trust_screen
@@ -171,7 +171,8 @@ impl OnboardingScreen {
                     app_server_request_handle,
                     auth_config,
                     bedrock_setup_enabled,
-                    animations_enabled: local_settings.tui.animations,
+                    animations_enabled: local_settings.tui.animations
+                        && local_settings.tui.effects.shimmer,
                     animations_suppressed: std::cell::Cell::new(false),
                 }));
             } else {