Remove arduino-esp32 dependency, modernise WiFi and SPI compat

- Replace Arduino WiFi.h in Networking.cpp with native esp_wifi/esp_netif;
  uses event-driven connect with FreeRTOS EventGroup and 30 s timeout
- Remove initArduino() / Arduino.h from main.cpp
- Remove deprecated arduino-esp32 submodule (was uninitialized and marked
  deprecated since it was first added in Dec 2021)
- rc522.h: guard VSPI_HOST → SPI3_HOST for ESP-IDF 5.x compatibility
- WebInterface.cpp: drop redundant esp_wifi.h (esp_netif.h is sufficient)
- CMakeLists.txt: add esp_wifi + nvs_flash to REQUIRES

https://claude.ai/code/session_01MhAnh68DPNnTjcKqjNYDmk

device/main/Networking.hpp

@@ -1,9 +1,10 @@
-#ifndef _NETWORKING_HPP
-#define _NETWORKING_HPP
+#pragma once
 
 class Networking {
-	public:
-		void connectWifi();
-};
+public:
+    /* Connects to the WiFi configured in Kconfig (CONFIG_ESP_WIFI_SSID / _PASSWORD).
+     * Blocks up to 30 s, then returns regardless of connection state. */
+    void connectWifi();
 
-#endif
+    bool isConnected() const;
+};