Watch for OS theme changes at runtime

docs/NATIVE-THEME-MIGRATION.md

@@ -169,11 +169,14 @@ and overwriting them fights its observer.
 - `Theme::change(mode, None, cx)` reproduces the native palette for the mode
   because the connector installed a `ThemeConfig` per variant.
 
-Known gap (not addressed here): gpui-component's system-appearance follow is
-driven by window-activation events. A live OS theme change while the window
-is focused may not propagate on Linux until the window is re-focused;
-native-theme's `watch` feature (a theme-change watcher) is a possible
-follow-up, out of scope.
+Known gap (addressed since): gpui-component's system-appearance follow is
+driven by window-activation events. The app now enables native-theme's
+`watch` feature and re-applies the theme on its signal (`start_theme_watcher`
+in `desktop/src/main.rs`), so live OS changes apply without re-focusing or
+restarting. macOS reports appearance changes only (`AppleInterfaceTheme-
+ChangedNotification`); an accent-only change posts a different notification
+the watcher does not observe yet — Windows (`UISettings::ColorValuesChanged`),
+KDE (inotify on `kdeglobals`) and GNOME (portal `SettingChanged`) cover accent.
 
 ### 4.4 Settings dialog (`settings_dialog.rs`)
 
@@ -278,6 +281,5 @@ Unchanged:
   SVG assets.
 - theme-drawn widgets (`widgets` feature).
 - a preset-picker UI (`from_preset`) in settings.
-- runtime OS-theme watching (`watch` feature).
 - per-field user overrides layered on the native theme.
 - migrating `signed.json` into a native-theme `Theme` definition.