[Critteros]

Problem

When a camera effect directly replaces another effect on the same track, the new effect gets no frames. Its video stops on the last frame. The changes effect -> null and null -> effect work

Cause

1. applyMiddleware in @fishjam-cloud/react-client starts the new effect, publishes it, then stops the old effect.
2. The old effect calls subscription.remove(), and remove() always calls processor.detach().
3. The native tap has one consumer slot per track, and detach() does not know which consumer calls it. It removes the new consumer and the tap of the track:
   • iOS: fj_detachTrackIdOnWorkerQueue and CameraFrameTap.detachConsumer
   • Android: TrackPrivate.releaseCameraFrameTap
4. The activeSubscriptions guard does not stop this. Its key is the processor handle, and getCameraFrameProcessor returns a new handle on each call.

Fix

Only the latest subscription of a track can detach. An older subscription still clears its own callback.

 remove()
   clear activeSubscriptions entry
-  processor.detach()
+  if latestSubscriptionByTrack[trackId] is this subscription
+    delete the entry
+    processor.detach()
   clear the callback

 attachCameraFrameCallback()
   processor.attach(consumer)
+  latestSubscriptionByTrack[trackId] = subscription

The map changes on the same JS tick as processor.attach, so it follows the order of the native slot. A failed attach does not change the map

[Magmusacy]

good job