Segmentation Editor: Integrate 3D viewer with the segmentation panel

Integrate the 3D segmentation viewer with the segmentation panel.

Tasks

• Panel <-> viewport state integration — segmentation table drives active segment, visibility (per segment and per representation), add/delete/lock/rename/recolor, and fill/outline styles across both 2D labelmap and 3D surface viewports, with bidirectional event propagation between the 2D and 3D representations. Implemented in oak-tree/medical-imaging/ohif-viewers!58 (SegmentationEditorPanel.jsx, SegmentationEditorLayout.js).
• Tool toggles — add tools so that it is possible to toggle between different Cornerstone utilities such as the paintbrush, livewire, and volumetric selector. No editing tools are registered in the new editor stack yet; voxel-level editing is not currently possible.
• Labelmap switching — add support to the viewport so that when another labelmap (DICOM-SEG series) is selected, it changes the active segmentation. Active-segment switching within the loaded labelmap works; selecting a different labelmap from the editor has no UI/plumbing yet.

See the implementation assessment against oak-tree/medical-imaging/ohif-viewers!58 in the comments (2026-07-10) for file-level detail.