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/touch/touch.cpp

@@ -0,0 +1,53 @@
+#include "touch.h"
+#include "common/constants.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/event_groups.h"
+// TODO: implement actual touch functionality
+
+TouchHandler::TouchHandler(QueueHandle_t touch_queue) {
+  (void)touch_queue;
+}
+
+TouchHandler::~TouchHandler() { }
+
+EInkTouchHandler::EInkTouchHandler(QueueHandle_t touch_queue)
+  : TouchHandler(touch_queue) { }
+
+EInkTouchHandler::~EInkTouchHandler() { }
+
+void EInkTouchHandler::init(EventGroupHandle_t system_event_group) {
+  if (system_event_group != NULL) {
+    xEventGroupSetBits(system_event_group, TOUCH_CALIBRATED_BIT);
+  }
+}
+
+void EInkTouchHandler::start_event_loop() {
+  // Minimal background task to represent touch processing
+  xTaskCreate(
+    // use static adapter and pass `this` as task parameter
+    EInkTouchHandler::task_adapter,
+    "touch_task",
+    2048,
+    this,
+    tskIDLE_PRIORITY + 1,
+    nullptr
+  );
+}
+
+// static
+void EInkTouchHandler::task_adapter(void* arg) {
+  EInkTouchHandler* self = static_cast<EInkTouchHandler*>(arg);
+  if (self) {
+    self->run_event_loop();
+  } else {
+    printf("EInkTouchHandler::task_adapter received null pointer\n");
+  }
+  vTaskDelete(NULL);
+}
+
+void EInkTouchHandler::run_event_loop() {
+  for (;;) {
+    vTaskDelay(pdMS_TO_TICKS(1000));
+  }
+}

main/touch/touch.h

@@ -0,0 +1,32 @@
+#include "info/info.h"
+
+class TouchHandler {
+public:
+  TouchHandler(QueueHandle_t touch_queue);
+  // the system_event_group is used to set touch-calibrated bit
+  virtual void init(EventGroupHandle_t system_event_group) = 0;
+  virtual void start_event_loop() = 0;
+  virtual ~TouchHandler() = 0;
+private:
+  TouchHandler(const TouchHandler&) = delete;
+  TouchHandler& operator=(const TouchHandler&) = delete;
+};
+
+class EInkTouchHandler : public TouchHandler {
+public:
+  EInkTouchHandler(QueueHandle_t touch_queue);
+  void init(EventGroupHandle_t system_event_group) override;
+  void start_event_loop() override;
+  ~EInkTouchHandler() override;
+
+private:
+  // Task adapter used for FreeRTOS task creation. Forwards to
+  // `run_event_loop()` using the `this` pointer passed as the task param.
+  static void task_adapter(void* arg);
+
+  // Instance method implementing the touch event loop.
+  void run_event_loop();
+  // prevent copying
+  EInkTouchHandler(const EInkTouchHandler&) = delete;
+  EInkTouchHandler& operator=(const EInkTouchHandler&) = delete;
+};