feat: add live multi-plane and 3d array views

tests/unit/array-builder-canvas.test.js

@@ -7,6 +7,7 @@ import {
   hitTestMicrophone,
   keyboardNudgeForKey,
   niceGridStep,
+  projectArrayPosition3d,
 } from "/apps/array-builder/canvas-view.js";
 
 function assertNear(actual, expected, tolerance, label) {
@@ -139,3 +140,29 @@ test("Array canvas grid와 keyboard nudge의 순수 helper가 1/2/5 및 y-up 규
   assertEqual(keyboardNudgeForKey("ArrowDown", 0.002, true).dy, -0.02, "shift multiplies by ten");
   assertEqual(keyboardNudgeForKey("Enter", 0.002), null, "non-arrow key ignored");
 });
+
+test("Array canvas 3D projection은 +Z FRONT와 right-handed XYZ를 보존한다", () => {
+  const frontView = {
+    yaw: 0,
+    pitch: 0,
+    centerPixelX: 200,
+    centerPixelY: 120,
+    centerHorizontal: 0,
+    centerVertical: 0,
+    scale: 100,
+  };
+  const positiveX = projectArrayPosition3d([1, 0, 0], frontView);
+  const positiveZ = projectArrayPosition3d([0, 0, 1], frontView);
+  const positiveY = projectArrayPosition3d([0, 1, 0], frontView);
+  assertNear(positiveX.x, 300, 1e-12, "+X projects right");
+  assertNear(positiveX.y, 120, 1e-12, "+X keeps screen height");
+  assertNear(positiveZ.x, 200, 1e-12, "+Z stays centered horizontally");
+  assertNear(positiveZ.y, 20, 1e-12, "+Z FRONT projects upward");
+  assertNear(positiveY.depth, -1, 1e-12, "+Y supplies front-view depth");
+
+  const edgeView = { ...frontView, pitch: Math.PI / 2 };
+  const edgeY = projectArrayPosition3d([0, 1, 0], edgeView);
+  const edgeZ = projectArrayPosition3d([0, 0, 1], edgeView);
+  assertNear(edgeY.y, 20, 1e-12, "orbiting exposes +Y vertically");
+  assertNear(edgeZ.depth, 1, 1e-12, "orbiting moves +Z onto the depth axis");
+});