Add active buzzer test with SoftSPI touch and LVGL.

GPIO22 digital on/off toggle (default off) and flashable firmware/cyd package.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/buzzer.cpp

@@ -0,0 +1,25 @@
+#include "buzzer.h"
+#include "pins.h"
+
+#include <Arduino.h>
+
+static bool g_on = false;
+
+static void apply() {
+  digitalWrite(BUZZER_PIN, g_on ? HIGH : LOW);
+}
+
+void buzzer_init() {
+  pinMode(BUZZER_PIN, OUTPUT);
+  g_on = false;
+  apply();
+  Serial.printf("Buzzer GPIO%d OFF (default)\n", BUZZER_PIN);
+}
+
+void buzzer_set_on(bool on) {
+  g_on = on;
+  apply();
+  Serial.printf("Buzzer %s\n", g_on ? "ON" : "OFF");
+}
+
+bool buzzer_is_on() { return g_on; }