fix: expose command_queue_init for testing by removing static

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

engine.h

@@ -142,6 +142,9 @@ int engine_submit_command(Engine *engine, CommandType type, int index, jack_nfra
 // Process pending commands (called from audio thread)
 void engine_process_commands(Engine *engine);
 
+// Initialize command queue (exposed for testing)
+void command_queue_init(CommandQueue *q);
+
 // Utility
 const char* clip_state_to_string(ClipState state);
 uint8_t clip_state_to_velocity(ClipState state);