Fix embed use-after-free, restore golden fixture + refs tests, drop dead note_entry

src/shell/instrument/processor_reload.cpp

@@ -232,7 +232,7 @@ void ReaSamplerProcessor::publishBuiltLocked(std::unique_ptr<LoadedInstrument> b
 
 void ReaSamplerProcessor::rebuildVoiceEngine() {
     // Off the audio thread. A voice-param change touches no audio data, so this rebuilds
-    // the engine around a copy of the live instrument's already-decoded keymap — no
+    // the engine around a copy of the live instrument's already-decoded SampleData — no
     // bridge, no disk — and publishes through the same drain-slot swap.
     std::lock_guard<std::mutex> lock(reloadMutex_);
     LoadedInstrument* cur = live_.load(std::memory_order_acquire);