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/native-main-lifecycle.spec.ts

@@ -3,7 +3,7 @@ import fs from "node:fs";
 import path from "node:path";
 
 test("repeated native object creation and deletion survives serialization", async ({ page }) => {
-  await page.goto("/");
+  await page.goto("/?engine=manual");
   const bytes = fs.readFileSync(path.resolve(import.meta.dirname, "../../../tests/files/web/basic_scene.blend"));
   const result = await page.evaluate(async (input) => {
     const { WebEngineClient } = await import("/src/engine-client/WebEngineClient.ts");