Add interactive drag control and kinematics benchmark

[only-one-over]

Summary

• add an RViz Interactive Marker target node that publishes dragged tool poses to /target_pose
• add an interactive Gazebo/RViz launch entry
• add dual-quaternion FK consistency support and fk_ik_benchmark for reproducible kinematics validation

Tests

• colcon build --symlink-install --event-handlers console_direct+
• ros2 run robot_arm_kinematics fk_ik_test
• ros2 run robot_arm_kinematics fk_ik_benchmark --samples 100 --seed 20250624