fix: update dark sidebar banner asset

Use the complete Pythinker wordmark as the canonical dark banner and keep the committed web bundle in sync.

Author: elkaix

apps/pythinker-code/dist-web/.web-bundle-manifest.json

@@ -1,4 +1,4 @@
 {
-  "sourceHash": "13d642ad4a687016ff3f0d83fb81084e67011f6e0a786737a4b76dc5c5e01fb4",
+  "sourceHash": "580a0ed072525532f878839fc3bf43d7ab6e870796c2e2f3a9e11800ee7c273e",
   "sourceFileCount": 404
 }