Refactor LVGL code into kernel module (#472)

* **New Features**
  * Added a standalone LVGL module and enabled LVGL support in the simulator for richer local UI testing.

* **Refactor**
  * HAL and LVGL split into distinct modules; startup and device attach/detach flows reorganized for clearer lifecycle management.
  * Public APIs tightened with clearer nullability/documentation.

* **Bug Fixes**
  * More consistent LVGL start/stop and device attach/detach behavior for improved stability.

TactilityFreeRtos/Include/Tactility/Thread.h

@@ -155,7 +155,7 @@ public:
         mutex.unlock();
     }
 
-    void setStateCallback(StateCallback callback, _Nullable void* callbackContext = nullptr) {
+    void setStateCallback(StateCallback callback, void* callbackContext = nullptr) {
         mutex.lock();
         assert(state == State::Stopped);
         stateCallback = callback;