Add support for fusing/unfusing JellyLMS zones into synchronized

multi-room groups, addressed by MAC (derived from the `lms-{mac}` device id).

src/lib/stores/playbackMode.ts

@@ -198,6 +198,12 @@ function createPlaybackModeStore() {
       // Get repository for handle (backend will fetch playback info via player_play_tracks)
       const repository = auth.getRepository();
 
+      // Mark the whole sequence as a transfer in the *Rust* manager too. Without
+      // this, player_play_tracks sees mode=Remote and casts the track back to the
+      // remote session instead of playing it locally (the frontend's own
+      // isTransferring flag is invisible to Rust). Cleared in `finally`.
+      await commands.playbackModeSetTransferring(true);
+
       // Start local playback (events allowed through because isTransferring=true)
       // Use player_play_tracks - backend fetches all metadata from single ID
       const repositoryHandle = repository.getHandle();
@@ -248,6 +254,14 @@ function createPlaybackModeStore() {
       console.error("Transfer to local failed:", error);
       throw error;
     } finally {
+      // Always lower the Rust transferring flag so it can't stick on if any step
+      // above threw (transfer_to_local lowers it on success, but not if we never
+      // reached it). Safe to call unconditionally.
+      try {
+        await commands.playbackModeSetTransferring(false);
+      } catch (e) {
+        console.warn("[PlaybackMode] Failed to clear transferring flag:", e);
+      }
       currentTransferAbort = null;
     }
   }