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/iotdis/settings/settings_handler.h

@@ -0,0 +1,45 @@
+#pragma once
+
+#include "freertos/FreeRTOS.h"
+#include <string>
+#include <memory>
+#include "io/nvs_handler.h"
+
+class SettingHandler {
+public:
+  SettingHandler(std::unique_ptr<NVSStorageHandler> storage) :
+    remote_ip_(""),
+    remote_port_(0),
+    local_port_(0),
+    storage_(std::move(storage)) { }
+  ~SettingHandler() = default;
+
+  esp_err_t init(const EventGroupHandle_t& system_event_group) {
+    storage_->init(system_event_group);
+    return ESP_OK;
+  }
+
+  void load_settings();
+  void save_settings(const std::string& ip, uint16_t port) {
+    save_settings(ip, port, local_port_);
+  }
+  void save_settings(const std::string& ip, uint16_t port, uint16_t local_port);
+
+  bool is_configured() const { return !remote_ip_.empty() && remote_port_ != 0 && local_port_ != 0; }
+
+  std::string get_remote_ip() const { return remote_ip_; }
+  uint16_t get_remote_port() const { return remote_port_; }
+  uint16_t get_local_port() const { return local_port_; }
+
+private:
+  static constexpr uint16_t DEFAULT_LOCAL_PORT = 4212;
+
+  static constexpr const char* NVS_KEY_IP = "bridge_ip";
+  static constexpr const char* NVS_KEY_PORT = "bridge_port";
+  static constexpr const char* NVS_KEY_LOCAL_PORT = "local_port";
+
+  std::string remote_ip_;
+  uint16_t remote_port_;
+  uint16_t local_port_;
+  std::unique_ptr<NVSStorageHandler> storage_;
+};