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/apps/app.h

@@ -5,6 +5,9 @@
 #include <string>
 #include <memory>
 
+// Forward declaration
+class InteractionHandler;
+
 /**
  * @brief Base class for all UI applications
  *
@@ -25,9 +28,10 @@ public:
    * between the header and navigation bar.
    *
    * @param container LVGL container object for this app
+   * @param interaction_handler Pointer to interaction handler for keyboard support
    * @return ESP_OK on success, error code otherwise
    */
-  virtual esp_err_t init(lv_obj_t* container) = 0;
+  virtual esp_err_t init(lv_obj_t* container, InteractionHandler* interaction_handler) = 0;
 
   /**
    * @brief Deinitialize and clean up app resources