Add 3-pin whistle sound sensor digital H/L detect on GPIO22.

Touch+LVGL UI shows QUIET/SOUND, pin level, hit count; no dB (digital only).

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

include/sound.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <stdint.h>
+
+void sound_init();
+void sound_poll();
+
+/** 当前是否检测到声音（已按 SOUND_ACTIVE_HIGH 解释） */
+bool sound_detected();
+
+/** 原始引脚电平：true=HIGH */
+bool sound_raw_high();
+
+/** 累计触发次数（边沿，带消抖） */
+uint32_t sound_event_count();
+
+/** 最近一次触发后经过的 ms；未触发过为 UINT32_MAX */
+uint32_t sound_ms_since_last();
+
+void sound_reset_count();