feat(web): enable UV editing in web UI and use OPFS save/reopen

- Forward workspace and mode to the native context in ?ui=web.
- Locate the writable native UV area; enter Edit explicitly and wait for
  project recovery locks before switching mode.
- Save projects to OPFS by default; add an explicit manual .blend download.
- Add UV E2E coverage and implementation status.

Co-Authored-By: Claude Code <noreply@anthropic.com>

web/tests/e2e/web-uv-workspace-gate.spec.ts

@@ -0,0 +1,90 @@
+import { expect, test } from "@playwright/test";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+const HERE = path.dirname(fileURLToPath(import.meta.url));
+const STUDIO = path.resolve(HERE, "../../app/public/tutorial/pbr/studio.blend");
+const GLB = path.resolve(HERE, "../../../re/猴头.glb");
+
+test.use({ viewport: { width: 1600, height: 900 } });
+
+async function openStudioAndMonkey(page: import("@playwright/test").Page): Promise<void> {
+  await page.goto("/?ui=web");
+  await page.locator("main.blender-app").waitFor({ timeout: 120_000 });
+  await page.locator('[data-testid="blend-file-input"]').setInputFiles(STUDIO);
+  await page.getByText(/Engine: SceneIR/).first().waitFor({ timeout: 120_000 });
+  await expect.poll(async () => page.getByTestId("scene-stats").innerText(), { timeout: 120_000 }).toMatch(/Objects 6/);
+  await page.locator('[data-testid="blend-file-input"]').setInputFiles(GLB);
+  await expect.poll(async () => page.getByTestId("scene-stats").innerText(), { timeout: 120_000 }).toMatch(/Objects 7/);
+}
+
+async function ensureEditMode(page: import("@playwright/test").Page): Promise<void> {
+  const status = page.locator('[data-testid="engine-status"]');
+  if ((await status.innerText()).includes("模式：Edit")) return;
+  try {
+    await expect(status).toContainText("模式：Edit", { timeout: 5_000 });
+    return;
+  }
+  catch { /* fall through to the explicit mode menu */ }
+  await page.locator(".mode-chip button").first().evaluate((element) => (element as HTMLElement).click());
+  const editMode = page.getByRole("menuitemcheckbox", { name: /编辑模式/ });
+  await editMode.waitFor({ timeout: 15_000 });
+  await editMode.evaluate((element) => (element as HTMLElement).click());
+  await expect(status).toContainText("模式：Edit", { timeout: 60_000 });
+  await page.keyboard.press("Escape");
+}
+
+async function openUVWorkspace(page: import("@playwright/test").Page): Promise<void> {
+  // The native desktop canvas can sit above the workspace tab at the same
+  // coordinates in headed Chromium; invoke the tab's DOM click directly.
+  await page.locator(".workspace-tabs button", { hasText: "UV Editing" }).evaluate((element) => (element as HTMLElement).click());
+  await expect(page.locator(".wasm-uv-editor")).toBeVisible({ timeout: 60_000 });
+  await expect(page.locator(".uv-controls")).toBeVisible({ timeout: 60_000 });
+  await expect.poll(async () => page.locator('[data-testid="editor-workflow-context"]').innerText(), { timeout: 60_000 })
+    .toContain("UV Editing");
+  // Desktop Blender's UV editor requires OB_MODE_EDIT (space_image.cc);
+  // enter Edit explicitly rather than depending on a startup timing quirk.
+  await ensureEditMode(page);
+  await expect.poll(async () => page.locator(".wasm-uv-editor").innerText(), { timeout: 60_000 }).toContain("原生 UV 选择");
+}
+
+async function selectAllAndUnwrap(page: import("@playwright/test").Page): Promise<void> {
+  await page.locator(".wasm-uv-editor button", { hasText: "全选 UV" }).evaluate((element) => (element as HTMLElement).click());
+  await expect.poll(async () => page.locator(".wasm-uv-editor").innerText(), { timeout: 60_000 }).toContain("UV 选择已提交");
+  await page.locator(".wasm-uv-editor button", { hasText: "展开所选 UV" }).evaluate((element) => (element as HTMLElement).click());
+  await expect.poll(async () => page.locator(".wasm-uv-editor").innerText(), { timeout: 60_000 }).toContain("展开 UV已提交");
+}
+
+test("UV Editing finds a writable native UV area and commits an unwrap", async ({ page }) => {
+  test.setTimeout(300_000);
+  await openStudioAndMonkey(page);
+  await openUVWorkspace(page);
+  await expect(page.locator('[data-testid="engine-status"]')).toContainText("模式：Edit", { timeout: 60_000 });
+
+  const before = Number(await page.locator("main.blender-app").getAttribute("data-project-snapshot-revision") ?? "0");
+  await selectAllAndUnwrap(page);
+  const after = Number(await page.locator("main.blender-app").getAttribute("data-project-snapshot-revision") ?? "0");
+  expect(after).toBeGreaterThan(before);
+});
+
+test("UV workspace survives save and reopen", async ({ page }) => {
+  test.setTimeout(360_000);
+  await openStudioAndMonkey(page);
+  await openUVWorkspace(page);
+  await selectAllAndUnwrap(page);
+
+  // Save through the OPFS project transaction (the download is a side effect
+  // of the same commit), then reload and reopen the recent OPFS project.
+  await page.locator('button[aria-label="保存项目"]').evaluate((element) => (element as HTMLElement).click());
+  await expect(page.locator("main.blender-app")).toHaveAttribute("data-user-action-save-status", "SUCCEEDED", { timeout: 60_000 });
+  await page.reload();
+  await page.locator("main.blender-app").waitFor({ timeout: 120_000 });
+  await expect.poll(async () => page.locator('[data-testid="recent-projects"] option').count(), { timeout: 60_000 }).toBeGreaterThan(1);
+  await page.locator('[data-testid="recent-projects"]').selectOption({ index: 1 });
+  const discard = page.getByRole("button", { name: "不保存，继续", exact: true });
+  if (await discard.count()) await discard.click();
+  await expect.poll(async () => page.getByTestId("scene-stats").innerText(), { timeout: 120_000 }).toMatch(/Objects 7/);
+  await openUVWorkspace(page);
+  await expect(page.locator(".uv-controls")).toBeVisible({ timeout: 60_000 });
+  await expect.poll(async () => page.locator(".wasm-uv-editor").innerText(), { timeout: 60_000 }).toContain("原生 UV 选择");
+});