Two leak paths surfaced after a flip-then-record-then-pop session
left the front camera claim stranded:
1. setDescription swapped instance.device without telling the plugin —
devicesInUse still held the original cameraId. After dispose,
releaseClaim only removed the *current* id, leaving the original
stuck. Next push of the page hit device_busy on the original cam.
Fix: setDescription handler now does a contention check, inserts
the new id and drops the old (or rolls back on swap failure).
2. create's catch path called releaseClaim(for: instance), but if
configureSession threw before instance.device was set,
instance.currentCameraId is nil — and the cameraId we inserted on
line above leaked. Fix: drop the known cameraId + audio claim
explicitly in the catch.
