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/web/web_handlers.h

@@ -0,0 +1,81 @@
+#pragma once
+
+#include "esp_http_server.h"
+#include <string>
+#include "network/web_server_handler.h"
+#include "ui/apps/iotdis/settings/settings_handler.h"
+#include "ui/apps/iotdis/bridge/bridge.h"
+
+/**
+ * @brief HTTP request handlers for Discord Bridge settings web interface
+ *
+ * These handlers serve the web configuration page and process
+ * settings updates and connection tests.
+ */
+class WebHandler {
+public:
+  WebHandler(
+    SettingHandler* setting_handler,
+    IotDisBridge* bridge
+  ) :
+    web_server_(std::make_unique<WebServerHandler>())
+    , setting_handler_(setting_handler)
+    , bridge_(bridge) { }
+  ~WebHandler();
+
+  esp_err_t start_web_server();
+  esp_err_t stop_web_server();
+
+  std::string get_url() const;
+  std::string get_device_ip() const;
+  uint16_t get_port() const;
+
+  bool is_running() const {
+    return web_server_ && web_server_->is_running();
+  }
+
+private:
+
+  std::string generate_auth_key_();
+
+  esp_err_t register_web_endpoints_();
+
+  /**
+   * @brief Serve the main settings configuration page
+   *
+   * Validates authentication and serves an HTML form with current settings.
+   * Requires auth query parameter matching the session key.
+   *
+   * @param req HTTP request object
+   * @return ESP_OK on success
+   */
+  static esp_err_t settings_page_handler_(httpd_req_t* req);
+
+  /**
+   * @brief Save bridge connection settings
+   *
+   * Parses POST data containing ip, port, and localPort fields.
+   * Validates and persists settings to NVS storage.
+   *
+   * @param req HTTP request object
+   * @return ESP_OK on success
+   */
+  static esp_err_t save_settings_handler_(httpd_req_t* req);
+
+  /**
+   * @brief Test connection to Discord bridge
+   *
+   * Creates temporary UDP client to test connectivity with provided settings.
+   * Returns JSON response indicating success or failure.
+   *
+   * @param req HTTP request object
+   * @return ESP_OK on success
+   */
+  static esp_err_t test_connection_handler_(httpd_req_t* req);
+
+  std::unique_ptr<WebServerHandler> web_server_;
+  SettingHandler* setting_handler_ = nullptr;  ///< Pointer to settings handler (not owned)
+
+  std::string auth_key_;
+  IotDisBridge* bridge_ = nullptr;      ///< Pointer to IotDisBridge (not owned)
+};