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/wav_list.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <Arduino.h>
+#include <stddef.h>
+#include <stdint.h>
+
+static constexpr size_t WAV_MAX = 24;
+static constexpr size_t WAV_PATH_MAX = 64;
+static constexpr size_t WAV_NAME_MAX = 28;
+
+struct WavTrack {
+  char path[WAV_PATH_MAX];
+  char name[WAV_NAME_MAX];
+  uint32_t bytes;
+};
+
+uint8_t wav_list_count();
+int8_t wav_list_selected();
+void wav_list_set_selected(int8_t idx);
+const WavTrack *wav_list_get(uint8_t idx);
+const char *wav_list_current_path();
+
+bool wav_list_scan();