chore: 框架科学优化前的完整基线

在开始'设备契约层 + 目录重构 + 通止规装配'改造之前，先钉住当前可运行状态，
使后续任何删除/重构都可回退。

本基线包含：
- 现有 ROS 2 工作区全部源码（arm_application / arm_control / arm_bringup 等）
- 官方 flexiv_ros2 栈（含 flexiv_hardware / flexiv_controllers 等符号链接）
- 设备契约层 src/arm_interfaces（新增，46 项单测通过）
- devices/ 设备选型与品牌清单（新增）
- scripts/gen_site_example.py 与由它生成的 config/site.example.yaml

按 .gitignore 排除：build/ / install/ / log/ / config/site.yaml / 模型权重二进制。

scripts/test_rdk_python.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+# Smoke-test Flexiv RDK Python against site robot (no ROS / no GitHub).
+set -euo pipefail
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+# shellcheck disable=SC1091
+source "${ROOT}/scripts/lib/load_site_config.sh" 2>/dev/null || true
+
+SN="${1:-${ROBOT_SN:-${SITE_ROBOT_SN:-Rizon4-063989}}}"
+ROBOT_IP="${ROBOT_IP:-${SITE_ROBOT_IP:-192.168.100.1}}"
+IFACE="${SITE_NET_IFACE:-}"
+PY="${RDK_PYTHON:-/home/cc/rdk_py310/bin/python}"
+
+echo "Using: ${PY}"
+echo "Robot SN: ${SN}  IP: ${ROBOT_IP}  iface: ${IFACE:-auto}"
+echo "Ping ${ROBOT_IP} ..."
+ping -c 1 -W 1 "${ROBOT_IP}" >/dev/null && echo "  network OK" || echo "  network FAIL"
+
+"${PY}" - <<PY
+import flexivrdk
+sn = "${SN}"
+iface = "${IFACE}"
+print("Connecting...", sn, "iface", iface or "auto")
+robot = None
+if iface:
+    for args in ((sn, [iface]), (sn, [iface], True), (sn, [iface], True, False)):
+        try:
+            robot = flexivrdk.Robot(*args)
+            break
+        except TypeError:
+            continue
+if robot is None:
+    robot = flexivrdk.Robot(sn)
+print("Connected. Clearing fault if any...")
+try:
+    robot.ClearFault()
+except Exception as e:
+    print("ClearFault:", e)
+mode = robot.mode()
+print("mode:", mode)
+states = robot.states()
+print("q:", list(states.q))
+print("OK — RDK Python link works. Enable RDK on teach pendant if mode/fault unexpected.")
+PY