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; }
 };

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

@@ -10,7 +10,7 @@
 
 class TpagerKeyboard final : public tt::hal::keyboard::KeyboardDevice {
 
-    lv_indev_t* _Nullable kbHandle = nullptr;
+    lv_indev_t* kbHandle = nullptr;
     gpio_num_t backlightPin = GPIO_NUM_NC;
     ledc_timer_t backlightTimer;
     ledc_channel_t backlightChannel;
@@ -45,7 +45,7 @@ public:
     bool stopLvgl() override;
 
     bool isAttached() const override;
-    lv_indev_t* _Nullable getLvglIndev() override { return kbHandle; }
+    lv_indev_t* getLvglIndev() override { return kbHandle; }
 
     bool setBacklightDuty(uint8_t duty);
     void makeBacklightImpulse();

Devices/lilygo-tlora-pager/Source/drivers/TloraPager.cpp

@@ -19,10 +19,10 @@ static int stop(Device* device) {
 Driver tlora_pager_driver = {
     .name = "T-Lora Pager",
     .compatible = (const char*[]) { "lilygo,tlora-pager", nullptr },
-    .startDevice = start,
-    .stopDevice = stop,
+    .start_device = start,
+    .stop_device = stop,
     .api = nullptr,
-    .deviceType = nullptr,
+    .device_type = nullptr,
     .owner = &device_module,
     .driver_private = nullptr
 };