gizmo

Transform gizmo — draggable translate/rotate/scale handles at the selection pivot. Handles draw through a debugViz provider; hit-testing and dragging use gizmo_math against the cursor's screenToRay. Each drag edits every selected entity through the entity proxy transform setters and is wrapped in a multiplayer undo operation, so a whole drag reverts as a single Ctrl+Z. The mode (translate / rotate / scale), the local/world space toggle, and the active drag live in module state; the editor scene entrypoint calls tick every frame and switches mode from the tool hotkeys. Handles size themselves to stay a roughly constant on-screen length, and holding the snap modifier quantizes translation to a grid, rotation to angle steps, and scale to fixed steps.