Snapshot Beep + WAV UI before Pomodoro rewrite.

Keep LEDC tones, TF WAV playback, and compact list layout as a tagged baseline.

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

include/sd_put.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <Arduino.h>
+
+// 串口协议:  "#PUT <path> <bytes>\n"  -> READY -> raw -> DONE/FAIL
+// 在 loop 里调用；返回 true 表示刚处理完一次传输
+bool sd_put_poll();