feat: dev-5.1 分支基线（v1.3.35 发版后代码 + 5.1 声道改造文档）

- 以 main(ccc65af) 为基线提交当前工作区代码
- 新增 5.1 声道改造文档两份
- .gitignore 补充 .vscode/、.screenshots/

test/voice_helper/control.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+# control.sh - 播放控制测试
+# 用法: control.sh <action> [k=v ...]
+#   action 取值（与文档 §6.1 CONTROL action 字段保持一致）:
+#     PLAY | PAUSE | FULLSCREEN_ENTER | FULLSCREEN_EXIT |
+#     SEEK_FORWARD | SEEK_BACKWARD | SEEK_TO |
+#     PREV | NEXT | SELECT_INDEX | PAGE_NEXT | PAGE_PREV | GOTO_PAGE
+#
+# 示例:
+#     control.sh PLAY
+#     control.sh SEEK_FORWARD seconds=10
+#     control.sh SEEK_TO seconds=300
+#     control.sh SELECT_INDEX index=3
+#     control.sh GOTO_PAGE page=2
+
+set -e
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck disable=SC1091
+source "${SCRIPT_DIR}/lib/common.sh"
+
+require_adb
+check_receiver_exists
+
+if [ $# -lt 1 ]; then
+  log_err "缺少 action"
+  echo "用法: $0 <action> [k=v ...]" >&2
+  exit 1
+fi
+
+ACTION="$1"; shift
+
+print_header "播放控制 CONTROL/${ACTION}"
+PAYLOAD=$(build_control_payload "${ACTION}" "$@")
+send_voice_broadcast "CONTROL" "${PAYLOAD}"
+log_ok "预期在播放页执行 ${ACTION}"