chore: add ROS2 build convenience script

Single-command colcon build helper for the common robostack configuration.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

ros2/build.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+set -e
+cd "$(dirname "$0")"
+source /opt/ros/humble/setup.bash
+colcon build --symlink-install "$@"
+echo ""
+echo "Done. Source with: source install/setup.bash"