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/library-append-main.spec.ts

@@ -14,7 +14,7 @@ delete desktopCanonical.sourceMarker;
 
 test("M12-03E keeps append undo/redo/save/reopen equal to the desktop canonical report", async ({ page }) => {
   test.setTimeout(120_000);
-  await page.goto("/");
+  await page.goto("/?engine=manual");
   const closure = {
     object: "Object/M12 Append Object",
     mesh: "Mesh/M12 Append Mesh",
@@ -167,6 +167,7 @@ test("M12-03E keeps append undo/redo/save/reopen equal to the desktop canonical
       const redone = await client.applyCommand({ type: "redo" });
       const redoneCanonical = await canonicalGraph(client, redone.snapshot, ids.image);
       const saved = await client.saveBlend();
+      client.terminate();
       const reopenedResult = await reopened.openBlend(saved);
       const reopenedClosure = closureState(reopenedResult.snapshot);
       const reopenedCanonical = await canonicalGraph(reopened, reopenedResult.snapshot, ids.image);