Apply OS theme via native-theme on desktop

crates/workspace/src/lib.rs

@@ -88,12 +88,15 @@ impl Workspace {
         let workspace = cx.entity().downgrade();
         let mut subscriptions = smallvec![];
 
-        subscriptions.push(
-            // Observe system appearance and update theme
-            cx.observe_window_appearance(window, |_this, window, cx| {
+        // Follow OS appearance changes only when the user has not pinned a
+        // mode; the native-theme watcher drives runtime changes either way.
+        // The `::settings` path is the external crate; the crate-local
+        // `settings` module is the preferences dialog.
+        if ::settings::AppSettings::get_appearance_mode(cx) == ::settings::AppearanceMode::System {
+            subscriptions.push(cx.observe_window_appearance(window, |_this, window, cx| {
                 gpui_kit::component::Theme::sync_system_appearance(Some(window), cx);
-            }),
-        );
+            }));
+        }
 
         subscriptions.push(
             // Subscribe to the nostr events