feat: add semantic motion system (#1320)

* feat: add semantic motion system

* feat: animate session workspace transitions

* feat: refine motion accessibility and transfer feedback

src/ui/tests/features/file-manager/TransferProgressBar.test.tsx

@@ -0,0 +1,61 @@
+import { cleanup, render, screen } from "@testing-library/react";
+import { afterEach, describe, expect, it } from "vitest";
+
+import { TransferProgressBar } from "../../../features/file-manager/components/TransferProgressBar";
+
+afterEach(cleanup);
+
+describe("TransferProgressBar", () => {
+  it("exposes determinate progress and drives the fill with a transform", () => {
+    const { container } = render(
+      <TransferProgressBar value={42} label="Uploading archive" />,
+    );
+
+    const progress = screen.getByRole("progressbar", {
+      name: "Uploading archive",
+    });
+    expect(progress.getAttribute("aria-valuenow")).toBe("42");
+    expect(progress.getAttribute("aria-busy")).toBe("false");
+    expect(
+      container
+        .querySelector<HTMLElement>(".transfer-progress-fill")
+        ?.style.getPropertyValue("--transfer-progress"),
+    ).toBe("0.42");
+  });
+
+  it("clamps invalid percentages before exposing them", () => {
+    const { rerender } = render(
+      <TransferProgressBar value={140} label="Uploading archive" />,
+    );
+
+    expect(screen.getByRole("progressbar").getAttribute("aria-valuenow")).toBe(
+      "100",
+    );
+
+    rerender(<TransferProgressBar value={-20} label="Uploading archive" />);
+    expect(screen.getByRole("progressbar").getAttribute("aria-valuenow")).toBe(
+      "0",
+    );
+  });
+
+  it("marks unknown and stalled progress without inventing a percentage", () => {
+    const { container } = render(
+      <TransferProgressBar label="Reconnecting" stalled />,
+    );
+
+    const progress = screen.getByRole("progressbar");
+    expect(progress.hasAttribute("aria-valuenow")).toBe(false);
+    expect(progress.getAttribute("aria-busy")).toBe("true");
+    expect(progress.getAttribute("data-stalled")).toBe("true");
+    expect(
+      container
+        .querySelector(".transfer-progress-fill")
+        ?.classList.contains("transfer-progress-indeterminate"),
+    ).toBe(true);
+    expect(
+      container
+        .querySelector(".transfer-progress-fill")
+        ?.classList.contains("transfer-progress-stalled"),
+    ).toBe(true);
+  });
+});