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/mesh-main-reader-production.spec.ts

@@ -12,7 +12,7 @@ const fixtureSha256 = crypto.createHash("sha256").update(fixture).digest("hex");
 
 test("WBV2 reads Mesh topology collections from Blender Main without JS simulation", async ({ page }) => {
   test.setTimeout(120_000);
-  await page.goto("/");
+  await page.goto("/?engine=manual");
   const result = await page.evaluate(async (inputs) => {
     const { WebEngineClient } = await import("/src/engine-client/WebEngineClient.ts");
     const summarize = (snapshot: any) => snapshot.meshes.map((mesh: any) => ({
@@ -38,6 +38,7 @@ test("WBV2 reads Mesh topology collections from Blender Main without JS simulati
         const meshes = summarize(opened.snapshot);
         if (meshes.length === 0) throw new Error("Blender Main returned no meshes");
         const saved = await client.saveBlend();
+        client.terminate();
         const reopened = await reopenedClient.openBlend(saved.slice(0));
         return { meshes, reopenedMeshes: summarize(reopened.snapshot), openedRevision: opened.snapshot.revision, reopenedRevision: reopened.snapshot.revision };
       }