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.

Modules/lvgl-module/Source/lvgl_module.c

@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-3.0-only
+#include <lvgl.h>
+#include <string.h>
+#include <tactility/module.h>
+#include <tactility/lvgl_module.h>
+
+
+error_t lvgl_arch_start();
+error_t lvgl_arch_stop();
+
+static bool is_running = false;
+static bool is_configured = false;
+
+struct LvglModuleConfig lvgl_module_config = {
+    NULL,
+    NULL,
+    0,
+    0,
+#ifdef ESP_PLATFORM
+    0,
+#endif
+};
+
+void lvgl_module_configure(const struct LvglModuleConfig config) {
+    is_configured = true;
+    memcpy(&lvgl_module_config, &config, sizeof(struct LvglModuleConfig));
+}
+
+static error_t start() {
+    if (!is_configured) {
+        return ERROR_INVALID_STATE;
+    }
+
+    if (is_running) {
+        return ERROR_NONE;
+    }
+
+    error_t result = lvgl_arch_start();
+    if (result == ERROR_NONE) {
+        is_running = true;
+    }
+
+    return result;
+}
+
+static error_t stop() {
+    if (!is_running) {
+        return ERROR_NONE;
+    }
+
+    error_t error = lvgl_arch_stop();
+    if (error == ERROR_NONE) {
+        is_running = false;
+    }
+
+    return error;
+}
+
+bool lvgl_is_running() {
+    return is_running;
+}
+
+struct Module lvgl_module = {
+    .name = "lvgl",
+    .start = start,
+    .stop = stop
+};