fix(14.1): guard metronome APVTS sync during prelisten mode

syncApvtsToAtomics() runs every processBlock and overwrites
config_metronome with the UI slider value, undoing the force-mute
set by PrelistenCommand. Skip metronome sync when prelisten_mode
is active so the zero volume persists.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mkschulze

juce/JamWideJuceProcessor.cpp

@@ -196,12 +196,17 @@ void JamWideJuceProcessor::syncApvtsToAtomics()
         client->config_mastermute.store(
             *apvts.getRawParameterValue("masterMute") >= 0.5f,
             std::memory_order_relaxed);
-        client->config_metronome.store(
-            *apvts.getRawParameterValue("metroVol"),
-            std::memory_order_relaxed);
-        client->config_metronome_mute.store(
-            *apvts.getRawParameterValue("metroMute") >= 0.5f,
-            std::memory_order_relaxed);
+        // During prelisten, metronome is force-muted by the run thread.
+        // Skip APVTS→atomic sync so the zero isn't overwritten every buffer.
+        if (!prelisten_mode.load(std::memory_order_relaxed))
+        {
+            client->config_metronome.store(
+                *apvts.getRawParameterValue("metroVol"),
+                std::memory_order_relaxed);
+            client->config_metronome_mute.store(
+                *apvts.getRawParameterValue("metroMute") >= 0.5f,
+                std::memory_order_relaxed);
+        }
     }
 }