The profile change handler was calling nam_host.set_block_size() AFTER
jack_client.start(), which means the JACK process callback started firing
with the new buffer size while the old NAM subprocess was still running
at the old block size. The pipe read/write byte counts desynchronized,
causing NAMEngineProcess.process() to return audio_block as passthrough
(direct input / DI signal) — every subsequent callback showed dry audio.
Fix: reload the NAM engine with the correct block size BEFORE restarting
the JACK client. Now when the process callback fires, the NAM subprocess
is already ready with the matching block size.
