chore: checkpoint web Blender feature-gap work, docs and tests

- update native web_engine sources and rebuilt wasm artifacts
- add task cards, status notes and tooling scripts
- add web e2e specs, tutorial UI sources and tutorial assets
- sync golden task manifests and audit records

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

web/tests/e2e/zz-debug-mode.spec.ts

@@ -0,0 +1,32 @@
+import { test, expect } from "@playwright/test";
+import path from "node:path";
+import { observeNative, exposeWebTools } from "../fixtures/native-ui-workflow";
+const root = path.resolve(import.meta.dirname, "../../..");
+
+function send(page: import("@playwright/test").Page, command: unknown) {
+  return page.evaluate((command) => new Promise((resolve) => {
+    const worker = (window as unknown as { __nativeWorkflowEngine: Worker }).__nativeWorkflowEngine;
+    const requestId = "debug-mode-" + crypto.randomUUID();
+    const timer = setTimeout(() => resolve({ timeout: true }), 60_000);
+    worker.addEventListener("message", function receive({ data }: MessageEvent) {
+      if (data.requestId !== requestId) return;
+      worker.removeEventListener("message", receive);
+      clearTimeout(timer);
+      resolve({ ok: data.ok, error: data.error, json: data.result?.json ?? data.json, snapshot: data.snapshot ? { editorWorkflowStatus: data.snapshot.editorWorkflowStatus, mode: data.snapshot.editorWorkflow?.context?.mode, activeObjectId: data.snapshot.activeObjectId } : undefined });
+    });
+    worker.postMessage({ requestId, command });
+  }), command);
+}
+
+test("debug web-only mode switch", async ({ page }) => {
+  await observeNative(page);
+  await page.goto("/");
+  await page.getByTestId("blend-file-input").setInputFiles(path.join(root, "tests/files/web/basic_scene.blend"));
+  await expect(page.getByTestId("engine-status")).toContainText(/SceneIR r\d+/, { timeout: 60_000 });
+  await exposeWebTools(page);
+  const before = await send(page, { type: "snapshot" });
+  const payload = JSON.stringify({ operator: "object.mode_set", native: true, properties: { mode: "EDIT", toggle: false }, areaType: "VIEW_3D", mode: "OBJECT" });
+  const source = `import json, web_blender\nweb_blender.desktop_operator(json.loads(${JSON.stringify(payload)}))`;
+  const result = await send(page, { type: "jsonCommand", cmd: "pythonExec", params: { source, filename: "DebugMode.py", console: false } });
+  console.log("MODE_DEBUG " + JSON.stringify({ before, result }).slice(0, 3000));
+});