fix: use pointer to dispatcher state in process callback for real-time access

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

engine.h

@@ -21,6 +21,8 @@ typedef struct {
     bool running;
     
     CarlaHost carla_host;  // Carla host state for plugin management
+    
+    AppState *state;  // Pointer to dispatcher's state (for real-time access)
 } Engine;
 
 int engine_init(Engine *engine, const char *client_name, DispatchFn dispatch);