Add HardwareRfid class implementation and integrate with main loop

src/main.cpp

@@ -1,17 +1,28 @@
 #include <Arduino.h>
 #include <hardware_led.hpp>
+#include <hardware_rfid.hpp>
 #include "hardware.pb.h"
 
 // Demo for HardwareLed
 HardwareLed led(2); // Assuming NeoPixel on pin 4 (D2 on ESP8266)
 
+// Demo for HardwareRfid
+HardwareRfid rfid(4, 5); // SS=D2 (GPIO4), RST=D1 (GPIO5)
+
 hardware_LedConfig configs[4];
 unsigned long lastChange = 0;
 int currentConfig = 0;
 
+void onRfidTag(const hardware_SensorToControlMessage& msg) {
+    Serial.print("RFID Tag detected: 0x");
+    Serial.println(msg.payload.rfid_reading.card_id, HEX);
+}
+
 void setup() {
   Serial.begin(9600);
   led.begin();
+  rfid.begin();
+  rfid.setCallback(onRfidTag);
 
   // Static config
   configs[0] = {0};
@@ -53,6 +64,7 @@ void setup() {
 
 void loop() {
   led.update();
+  rfid.update();
 
   if (millis() - lastChange >= 10000) {
     lastChange = millis();