chatgui: move SoundManager shutdown to ~MainWindow before node cleanup

- SoundManager::shutdown() called explicitly in ~MainWindow (not static destruction)
- Before ma_engine_uninit: DEBUG_INFO diagnostic in timestamped log
- After ma_engine_uninit: DEBUG_INFO diagnostic
- Double-call safe: static destructor hits m_initialized=false, returns immediately

tools/chatgui/src/sound_manager.cpp

@@ -3,6 +3,7 @@
 #include "sound_manager.h"
 #include <QFile>
 #include <QDebug>
+#include "../../lib/debug_config.h"
 
 SoundManager* SoundManager::instance() {
     static SoundManager s;
@@ -36,9 +37,10 @@ void SoundManager::shutdown() {
     }
     m_sounds.clear();
 
+    DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "SoundManager: before ma_engine_uninit engine=%p", (void*)m_engine);
     if (m_engine) { ma_engine_uninit(m_engine); delete m_engine; m_engine = nullptr; }
+    DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "SoundManager: after ma_engine_uninit");
     m_initialized = false;
-    qDebug("SoundManager: shutdown");
 }
 
 void SoundManager::setEnabled(bool enabled) { m_enabled = enabled; }