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/package.json

@@ -294,10 +294,12 @@
     "@ffmpeg/core": "^0.12.10",
     "@ffmpeg/ffmpeg": "^0.12.15",
     "@ffmpeg/util": "^0.12.2",
+    "@webgpu/glslang": "0.0.15",
+    "@xyflow/react": "12.12.1",
     "fflate": "0.8.3",
     "naga-wasm": "30.1.0",
-    "@webgpu/glslang": "0.0.15",
     "react": "19.2.8",
+    "react-accessible-treeview": "2.11.2",
     "react-dom": "19.2.8"
   },
   "devDependencies": {