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.

Devices/lilygo-tlora-pager/Source/devices/TpagerEncoder.h

@@ -5,7 +5,7 @@
 
 class TpagerEncoder final : public tt::hal::encoder::EncoderDevice {
 
-    lv_indev_t* _Nullable encHandle = nullptr;
+    lv_indev_t* encHandle = nullptr;
     pcnt_unit_handle_t encPcntUnit = nullptr;
 
     bool initEncoder();
@@ -26,5 +26,5 @@ public:
 
     int getEncoderPulses() const;
 
-    lv_indev_t* _Nullable getLvglIndev() override { return encHandle; }
+    lv_indev_t* getLvglIndev() override { return encHandle; }
 };