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/build_flexiv_rdk.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+# Build Flexiv RDK v1.x into ~/flexiv_install (required for real robot / flexiv_hardware).
+set -euo pipefail
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+RDK="${ROOT}/src/flexiv_rdk"
+PREFIX="${FLEXIV_INSTALL_PREFIX:-$HOME/flexiv_install}"
+
+if [[ ! -d "$RDK" ]]; then
+  echo "Missing $RDK — run scripts/fetch_flexiv.sh first"
+  exit 1
+fi
+
+echo "Building RDK thirdparty deps into $PREFIX ..."
+# Prefer system /opt/ros if present; else conda env already has compilers
+if [[ -f /opt/ros/humble/setup.bash ]]; then
+  # shellcheck disable=SC1091
+  source /opt/ros/humble/setup.bash
+fi
+
+cd "$RDK"
+if [[ -f thirdparty/build_and_install_dependencies_not_in_ros2.sh ]]; then
+  bash thirdparty/build_and_install_dependencies_not_in_ros2.sh "$PREFIX"
+elif [[ -f thirdparty/build_and_install_dependencies.sh ]]; then
+  bash thirdparty/build_and_install_dependencies.sh "$PREFIX"
+else
+  echo "No thirdparty build script found; see RDK README"
+  ls thirdparty || true
+fi
+
+rm -rf build && mkdir build && cd build
+cmake .. -DCMAKE_INSTALL_PREFIX="$PREFIX" -DCMAKE_BUILD_TYPE=Release
+cmake --build . --target install -j"$(nproc)"
+echo "RDK installed to $PREFIX"
+echo "Then: cd $ROOT && colcon build --symlink-install --cmake-args -DCMAKE_PREFIX_PATH=$PREFIX"