Add tests for box brush commands, E2E, geometry, and update scene document serialization test

tests/geometry/box-brush-geometry.test.ts

@@ -0,0 +1,40 @@
+import { describe, expect, it } from "vitest";
+
+import { createBoxBrush } from "../../src/document/brushes";
+import { getBoxBrushBounds, getBoxBrushCornerPositions } from "../../src/geometry/box-brush";
+
+describe("box brush geometry", () => {
+  it("builds finite bounds and eight corner positions from canonical box data", () => {
+    const brush = createBoxBrush({
+      center: {
+        x: 2,
+        y: 4,
+        z: -3
+      },
+      size: {
+        x: 6,
+        y: 2,
+        z: 4
+      }
+    });
+
+    expect(getBoxBrushBounds(brush)).toEqual({
+      min: {
+        x: -1,
+        y: 3,
+        z: -5
+      },
+      max: {
+        x: 5,
+        y: 5,
+        z: -1
+      }
+    });
+
+    const corners = getBoxBrushCornerPositions(brush);
+
+    expect(corners).toHaveLength(8);
+    expect(new Set(corners.map((corner) => `${corner.x}:${corner.y}:${corner.z}`)).size).toBe(8);
+    expect(corners.every((corner) => Number.isFinite(corner.x) && Number.isFinite(corner.y) && Number.isFinite(corner.z))).toBe(true);
+  });
+});