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/interaction_handler.h

@@ -28,9 +28,10 @@ public:
    *
    * Sets up necessary event listeners and state.
    *
+   * @param parent_container Parent container for keyboard (typically the screen)
    * @return ESP_OK on success, error code otherwise
    */
-  esp_err_t init(lv_obj_t* app_container);
+  esp_err_t init(lv_obj_t* parent_container);
 
   /**
    * @brief Deinitialize the Interaction Handler
@@ -58,8 +59,8 @@ private:
   esp_err_t show_keyboard_for_textarea_(lv_obj_t* textarea);
   esp_err_t hide_keyboard_(void);
 
-  // Pointers to key UI objects, owned by UIHandler
-  lv_obj_t* app_container_ = nullptr;
+  // Parent container (typically screen), reference only
+  lv_obj_t* parent_container_ = nullptr;
   // owned keyboard object
   lv_obj_t* keyboard_ = nullptr;
   // Currently focused textarea, reference only