chore: Clean up obsolete files and add Puppeteer chat test

- Remove obsolete documentation, examples, and utility scripts
- Remove temporary screenshots and test files from root
- Add test_chat_backend.js for Puppeteer testing of chat RAG
- Update .gitignore

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.claude/settings.local.json

@@ -68,7 +68,9 @@
       "Bash(fi)",
       "WebSearch",
       "WebFetch(domain:weaviate.io)",
-      "WebFetch(domain:docs.weaviate.io)"
+      "WebFetch(domain:docs.weaviate.io)",
+      "Bash(stat:*)",
+      "Bash(set PYTHONPATH=C:GitHublinear_coding_library_raggenerationslibrary_rag)"
     ]
   }
 }