No track is created; no routing changes. No selected track -> bank
import proceeds, instrument placement is refused with a console message
explaining why. createTrackWithInstrument removed (was sole caller).
Repurpose INGEST_IMPORT_MEDIA_EXPLORER to stand up a fresh instrument on
a new track pre-loaded with the imported sound, instead of force-selecting
on the active instance.
Repurpose INGEST_IMPORT_MEDIA_EXPLORER (id unchanged) to stand up a
fresh ReaSampler 9000 on a new named track pre-loaded with the imported
sound, instead of force-selecting on the active instance. One undo point.
On chunk-write failure, call TrackFX_Delete(track, fxIndex) to remove
the just-added empty FX instance before returning false. Signature
verified at reaper_plugin_functions.h:7236. Update the header comment
from "leaves at most the added FX" to the new all-or-nothing contract.
daniel