scene 0.4.0

• GizmoOrthographicVolume draws an orthographic camera's view volume, sized by a bound fit mode, extents, zoom, and offset.
• NodeSpec.shadowCastingMode carries a node's shadow casting mode (off, on, doubleSided, shadowsOnly), delta-serialized and overridable on prefab instances through the shadowCasting path.
• EnvironmentEffectsSpec carries SMAA quality (smaaThreshold, smaaMaxSearchSteps, smaaMaxDiagonalSearchSteps, smaaCornerRounding), delta-serialized like the other effects.
• The spec's temporal anti-aliasing defaults now match the renderer's.
• SceneDocument.editor (EditorStateSpec, EditorCameraSpec) carries the editor camera pose and selection.
• Added grid mesh splitting shared by editors and import pipelines: splitTriangleMeshByGrid bins whole triangles by world-space centroid into per-cell vertex/index buffers, and applyMeshSplitHints applies -split<N> node-name hints across a document (split children named Ground_x0_z3, hint stripped, orphaned source data removed).
• Added documentWorldMatrix, countResourceReferences, and isPayloadReferenced document utilities.
• Documents keep data this build does not read through a load and save. Unknown keys ride on the document, its specs, and their nested value objects (unknown), unknown .fsceneb chunks on SceneDocument.unknownChunks (UnknownChunk), and a property value with an unknown tag loads as an inert UnknownValue instead of failing the document.
• Added encodeNode, which encodes one node the way encodeDocument does.

Development funded by our sponsors, Primio (Silver).