feat: add release-to-move TCP gizmo control in Webots

Add a native Webots marker for setting the active tool's TCP position and
orientation. Dragging edits the preview; releasing the mouse submits one
complete, checked joint trajectory with configured TCP speed limits.
Unreachable targets reset the marker to the current TCP.

Preserve coordinate, joint, and control-file commands through motion
reservations and a controller action proxy. Give the gizmo lowest priority
and finish its committed trajectory before dispatching queued regular
commands, including waits longer than the former two-second service timeout.

Place the patron TCP at its working end, 55.2 mm along local Z, and use the
flange TCP when no tool is attached. Add digital_twin.tcp_gizmo configuration,
ROS interfaces, launch integration, and regression coverage.

Document operation, configuration, tool attachment, speed limits, and
troubleshooting in both Russian and English.

Validation: 42 Python tests and 8 C++ tests passed. Webots regressions covered
one action per release, translation and rotation with and without a tool,
unreachable targets, and ordinary commands waiting for gizmo completion.

src/iiwa_bringup/launch/iiwa.launch.py

@@ -90,6 +90,7 @@ def _runtime_setup(context, *args, **kwargs):
                 "controller_timer": str(settings.digital_twin.webots.controller_timer),
                 "controller": str(settings.controller.controller_path),
                 "initial_positions_file": str(settings.controller.moveit.initial_positions),
+                "tcp_gizmo_enabled": str(settings.digital_twin.tcp_gizmo.enabled).lower(),
             }.items(),
         ))