Add main application logic and touch handling functionality

- Implemented main application entry point in main.cpp, initializing queues and event groups.
- Created TouchHandler and EInkTouchHandler classes for handling touch events.
- Added a minimal event loop for touch processing in touch.cpp.
- Introduced unit tests for the hello world application in pytest_hello_world.py.
- Added configuration files for CI and Wokwi support.
- Created empty header files for network and UI modules.

main/display/display.cpp

@@ -0,0 +1,62 @@
+#include "display.h"
+#include "common/constants.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/event_groups.h"
+// TODO: implement actual display functionality
+
+DisplayHandler::DisplayHandler(QueueHandle_t touch_queue, SemaphoreHandle_t lvgl_mutex) {
+  (void)touch_queue;
+  (void)lvgl_mutex;
+}
+
+DisplayHandler::~DisplayHandler() { }
+
+EInkDisplayHandler::EInkDisplayHandler(QueueHandle_t touch_queue, SemaphoreHandle_t lvgl_mutex)
+  : DisplayHandler(touch_queue, lvgl_mutex) { }
+
+EInkDisplayHandler::~EInkDisplayHandler() { }
+
+void EInkDisplayHandler::init(EventGroupHandle_t system_event_group) {
+  if (system_event_group != NULL) {
+    xEventGroupSetBits(system_event_group, DISPLAY_READY_BIT);
+  }
+}
+void EInkDisplayHandler::start_event_loop() {
+  // Minimal background task to represent display processing
+  xTaskCreate(
+    // use the static adapter and pass `this` as the task parameter
+    EInkDisplayHandler::task_adapter,
+    "display_task",
+    2048,
+    this,
+    tskIDLE_PRIORITY + 1,
+    nullptr
+  );
+}
+
+// static
+void EInkDisplayHandler::task_adapter(void* arg) {
+  EInkDisplayHandler* self = static_cast<EInkDisplayHandler*>(arg);
+  if (self) {
+    self->run_event_loop();
+  } else {
+    printf("EInkDisplayHandler::task_adapter received null pointer\n");
+  }
+  // If run_event_loop ever returns, delete the task.
+  vTaskDelete(NULL);
+}
+
+void EInkDisplayHandler::run_event_loop() {
+  for (;;) {
+    vTaskDelay(pdMS_TO_TICKS(1000));
+  }
+}
+
+shutdown_display_handlerFunc EInkDisplayHandler::get_shutdown_display_handler() {
+  return nullptr;
+}
+
+restart_display_handlerFunc EInkDisplayHandler::get_restart_display_handler() {
+  return nullptr;
+}

main/display/display.h

@@ -0,0 +1,42 @@
+#include "info/info.h"
+
+typedef void (*shutdown_display_handlerFunc)(void);
+typedef void (*restart_display_handlerFunc)(void);
+
+class DisplayHandler {
+public:
+  DisplayHandler(QueueHandle_t touch_queue, SemaphoreHandle_t lvgl_mutex);
+  // the system_event_group is used to set display-ready bit
+  virtual void init(EventGroupHandle_t system_event_group) = 0;
+  virtual void start_event_loop() = 0;
+  // get a handler to perform display shutdown cleanup, this is called after event loop ends and DisplayHandler is deleted
+  virtual shutdown_display_handlerFunc get_shutdown_display_handler() = 0;
+  virtual restart_display_handlerFunc get_restart_display_handler() = 0;
+  virtual ~DisplayHandler() = 0;
+
+private:
+  DisplayHandler(const DisplayHandler&) = delete;
+  DisplayHandler& operator=(const DisplayHandler&) = delete;
+};
+
+class EInkDisplayHandler : public DisplayHandler {
+public:
+  EInkDisplayHandler(QueueHandle_t touch_queue, SemaphoreHandle_t lvgl_mutex);
+  void init(EventGroupHandle_t system_event_group) override;
+  void start_event_loop() override;
+  shutdown_display_handlerFunc get_shutdown_display_handler() override;
+  restart_display_handlerFunc get_restart_display_handler() override;
+  ~EInkDisplayHandler() override;
+
+private:
+  // Task adapter used for FreeRTOS task creation. It forwards to the
+  // instance `run_event_loop()` method using the `this` pointer passed
+  // as the task parameter.
+  static void task_adapter(void* arg);
+
+  // Instance method that implements the display task loop.
+  void run_event_loop();
+  // prevent copying
+  EInkDisplayHandler(const EInkDisplayHandler&) = delete;
+  EInkDisplayHandler& operator=(const EInkDisplayHandler&) = delete;
+};