refactor(web): split touch canvas adapters

apps/web/src/hooks/timelineTouchAdapters.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it } from "vitest";
+import { createTouchCanvasPointerEvent, createTouchMouseDownEvent } from "./timelineTouchAdapters.js";
+
+describe("timelineTouchAdapters", () => {
+  it("creates a primary-button mouse-down adapter for touch handlers", () => {
+    const currentTarget = new EventTarget();
+
+    expect(createTouchMouseDownEvent({ clientX: 42, clientY: 17 }, currentTarget)).toMatchObject({
+      button: 0,
+      clientX: 42,
+      currentTarget,
+      shiftKey: false,
+    });
+  });
+
+  it("allows missing targets when creating a touch mouse-down adapter", () => {
+    const event = createTouchMouseDownEvent({ clientX: 7, clientY: 9 });
+
+    expect(event.currentTarget).toBeNull();
+    expect(() => {
+      event.preventDefault();
+      event.stopPropagation();
+    }).not.toThrow();
+  });
+
+  it("creates a canvas pointer event with both coordinates preserved", () => {
+    expect(createTouchCanvasPointerEvent({ clientX: 21, clientY: 34 })).toEqual({
+      clientX: 21,
+      clientY: 34,
+    });
+  });
+});