Improve Android radio capture lifecycle, VAD and PTT controls

src/chat/chat_setting.c

@@ -44,7 +44,6 @@ static const struct chat_setting_def g_setting_defs[] = {
     {"radio_compressor_max_gain_db",CHAT_SETTING_INT,  15,  1, 100},
     {"radio_vad_enabled",           CHAT_SETTING_BOOL, 0,   0, 1},
     {"radio_vad_threshold",         CHAT_SETTING_INT,  50, 10, 95},   /* порог вероятности речи, % */
-    {"radio_vad_pre_roll_ms",       CHAT_SETTING_INT,  200, 0, 500},  /* pre-roll перед срабатыванием */
     {"radio_vad_hangover_ms",       CHAT_SETTING_INT,  200, 50, 2000},/* тишина до авто-отбоя */
     {"media_download_max_peers",    CHAT_SETTING_INT,  3,   1, 16},
     {"storage_backfill_days",       CHAT_SETTING_INT,  7,   1, 365},