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/rig-pose-authoring-native.spec.ts

@@ -17,7 +17,7 @@ for (const route of ["bones", "pose"] as const) {
     const receipts = process.env.WBV2_RECEIPT_DIR ?? testInfo.outputPath("receipts");
     const directory = path.join(receipts, `rig-${route}-artifacts`);
     fs.mkdirSync(directory, { recursive: true });
-    await page.goto("/");
+    await page.goto("/?engine=manual");
     const result = await page.evaluate(async input => {
       const { WebEngineClient } = await import("/src/engine-client/WebEngineClient.ts");
       const clients: InstanceType<typeof WebEngineClient>[] = [];
@@ -58,9 +58,11 @@ for (const route of ["bones", "pose"] as const) {
         await save(client, "undo");
         await client.applyCommand({ type: "redo" });
         const saved = await save(client, "redo");
+        client.terminate();
         const reopen = create();
         await reopen.openBlend(saved.slice(0));
         await save(reopen, "reopened");
+        reopen.terminate();
         const repeat = create();
         await repeat.openBlend(Uint8Array.from(input.bytes).buffer);
         await repeat.applyCommand(command);