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>

test-results/.last-run.json

@@ -1,6 +1,4 @@
 {
   "status": "failed",
-  "failedTests": [
-    "44d526552dd243783a40-2cb37a5217f2f6418146"
-  ]
+  "failedTests": []
 }