✅(frontend) add unsupported file preview e2e tests

Cover the fallback viewer that kicks in for file types the app
cannot render inline. A minimal .bin fixture exercises the redesign
so the filename, the "Unsupported format." disclaimer and the
secondary download button are all checked end to end.

src/frontend/apps/e2e/__tests__/app-drive/assets/test-unsupported.bin

@@ -0,0 +1 @@
+This is an unsupported binary fixture file.

src/frontend/apps/e2e/__tests__/app-drive/file-preview/unsupported-file-preview.spec.ts

@@ -0,0 +1,64 @@
+import path from "path";
+
+import test, { expect } from "@playwright/test";
+
+import { clearDb, login } from "../utils-common";
+import { clickToMyFiles } from "../utils-navigate";
+import { uploadFile } from "../utils/upload-utils";
+
+const UNSUPPORTED_FILE_PATH = path.join(
+  __dirname,
+  "../assets/test-unsupported.bin",
+);
+
+test.describe("Unsupported File Preview", () => {
+  test.beforeEach(async ({ page }) => {
+    await clearDb();
+    await login(page, "drive@example.com");
+    await page.goto("/");
+    await clickToMyFiles(page);
+
+    await uploadFile(page, UNSUPPORTED_FILE_PATH);
+    await expect(
+      page.getByRole("cell", { name: "test-unsupported.bin", exact: true }),
+    ).toBeVisible({ timeout: 10000 });
+
+    await page
+      .getByRole("cell", { name: "test-unsupported.bin", exact: true })
+      .dblclick();
+    await expect(page.getByTestId("file-preview")).toBeVisible({
+      timeout: 10000,
+    });
+  });
+
+  test("Renders the NotSupportedPreview for an unknown binary file", async ({
+    page,
+  }) => {
+    const unsupported = page.locator(".file-preview-unsupported");
+    await expect(unsupported).toBeVisible();
+
+    await expect(
+      unsupported.locator(".file-preview-unsupported__title"),
+    ).toHaveText("test-unsupported.bin");
+  });
+
+  test("Download button in the unsupported view triggers a download", async ({
+    page,
+  }) => {
+    const downloadButton = page.locator(
+      ".file-preview-unsupported__download-button",
+    );
+    await expect(downloadButton).toBeVisible();
+
+    const downloadPromise = page.waitForEvent("download");
+    await downloadButton.click();
+    const download = await downloadPromise;
+
+    expect(download.suggestedFilename()).toContain("test-unsupported");
+  });
+
+  test("Hides the actions menu for unsupported files", async ({ page }) => {
+    const filePreview = page.getByTestId("file-preview");
+    await expect(filePreview.getByText("more_vert")).not.toBeVisible();
+  });
+});