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.

Tactility/Source/hal/usb/Usb.cpp

@@ -20,7 +20,7 @@ struct BootModeData {
 static Mode currentMode = Mode::Default;
 static RTC_NOINIT_ATTR BootModeData bootModeData;
 
-sdmmc_card_t* _Nullable getCard() {
+sdmmc_card_t* getCard() {
     auto sdcards = findDevices<sdcard::SpiSdCardDevice>(Device::Type::SdCard);
 
     std::shared_ptr<sdcard::SpiSdCardDevice> usable_sdcard;

Tactility/Source/hal/usb/UsbTusb.cpp

@@ -19,7 +19,7 @@
 static const auto LOGGER = tt::Logger("USB");
 
 namespace tt::hal::usb {
-    extern sdmmc_card_t* _Nullable getCard();
+    extern sdmmc_card_t* getCard();
 }
 
 enum {