feat: Implement Discord app UI and settings management

- Added MainUI class for displaying voice state, status icon, and buttons.
- Introduced MainUIHandler to manage UI interactions and bridge communication.
- Created SettingsUI for displaying QR code and configuration instructions.
- Implemented SettingsUIHandler to manage settings and web server interactions.
- Developed WebHandler for handling HTTP requests for settings configuration.
- Updated AppRegistry to initialize with the new Discord app descriptor.
- Enhanced InteractionHandler to support keyboard interactions across app switches.
- Updated UIHandler to manage app switching and rendering of app icons.
- Enabled QR code support in LVGL configuration.

main/ui/ui_handler.cpp

@@ -1,8 +1,14 @@
 #include "ui/ui_handler.h"
+#include "ui/apps/registry.h"
 #include "esp_log.h"
 
 #define TAG "UIHandler"
 
+struct AppClickUserData {
+  UIHandler* ui_handler;
+  std::string app_name;
+};
+
 UIHandler::~UIHandler() {
   deinit();
 }
@@ -18,7 +24,9 @@ esp_err_t UIHandler::init(void) {
     return ret;
   }
 
-  ret = interaction_handler_.init(root_layout_.get_app_container());
+  // Initialize InteractionHandler with screen as parent (not app_container)
+  // so keyboard survives app switches
+  ret = interaction_handler_.init(screen);
   if (ret != ESP_OK) {
     ESP_LOGE(TAG, "Failed to initialize InteractionHandler");
     return ret;
@@ -61,7 +69,7 @@ esp_err_t UIHandler::deinit(void) {
   return ESP_OK;
 }
 
-esp_err_t UIHandler::switch_app(std::shared_ptr<AppDescriptor> app_descriptor) {
+esp_err_t UIHandler::switch_app(AppDescriptor* app_descriptor) {
   if (!app_descriptor) {
     ESP_LOGE(TAG, "Invalid app descriptor");
     return ESP_ERR_INVALID_ARG;
@@ -100,7 +108,7 @@ esp_err_t UIHandler::switch_app(std::shared_ptr<AppDescriptor> app_descriptor) {
     return ESP_ERR_INVALID_STATE;
   }
 
-  ret = new_app->init(app_container);
+  ret = new_app->init(app_container, &interaction_handler_);
   if (ret != ESP_OK) {
     ESP_LOGE(TAG, "Failed to initialize app: %s", new_app->get_name().c_str());
     active_descriptor_ = nullptr;
@@ -239,6 +247,45 @@ esp_err_t UIHandler::create_main_screen_(lv_obj_t* parent) {
     return ret;
   }
 
+  // render all apps
+
+  for (const auto& [name, descriptor] : AppRegistry::instance()) {
+    lv_obj_t* app_icon_container = lv_obj_create(root_layout_.get_app_container());
+    lv_obj_set_size(app_icon_container, 100, 100);
+    lv_obj_set_style_pad_all(app_icon_container, 10, 0);
+    lv_obj_set_flex_flow(app_icon_container, LV_FLEX_FLOW_COLUMN);
+    lv_obj_set_flex_align(app_icon_container, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);
+
+    // Draw the app icon
+    descriptor->draw_icon(app_icon_container);
+
+    // App name label
+    lv_obj_t* label = lv_label_create(app_icon_container);
+    lv_label_set_text(label, name.c_str());
+    lv_obj_set_style_text_align(label, LV_TEXT_ALIGN_CENTER, 0);
+
+    // Center the icon container
+    lv_obj_center(app_icon_container);
+
+    // Register click event to switch to the app
+    lv_obj_add_event_cb(app_icon_container,
+      [](lv_event_t* e) {
+        AppClickUserData* user_data = static_cast<AppClickUserData*>(lv_event_get_user_data(e));
+        UIHandler* ui_handler = user_data->ui_handler;
+        std::string app_name = user_data->app_name;
+
+        AppDescriptor* descriptor = AppRegistry::instance()[app_name];
+        if (descriptor) {
+          ui_handler->switch_app(descriptor);
+        } else {
+          ESP_LOGE(TAG, "App descriptor not found for app: %s", app_name.c_str());
+        }
+      },
+      LV_EVENT_CLICKED,
+      new AppClickUserData { this, name }
+    );
+  }
+
   // Register back button callback
   lv_event_dsc_t* back_event_dsc = nullptr;
   ret = root_layout_.register_back_button_callback(