Monorepo Integration: Unified Backend, Frontend & Documentation

- Reorganize project into monorepo structure
  - backend/app/ - New FastAPI backend (modular with src/)
  - backend/legacy/ - Legacy database modules (relational & vector)
  - frontend/ - React text editor application

- Add launcher.py for easy full-stack startup
- Complete documentation in README.md
  - Quick start guide
  - API endpoints reference
  - Development setup
  - Troubleshooting

- Refactor main.py to 35 lines (app configuration only)
- Update .gitignore for full-stack project
- Add CHANGELOG.md with version history (v0.1.0-v0.1.1)

Structure is now clean and ready for team collaboration.

backend/legacy/local_model_miniLM/config_sentence_transformers.json

@@ -0,0 +1,14 @@
+{
+  "__version__": {
+    "sentence_transformers": "5.3.0",
+    "transformers": "5.3.0",
+    "pytorch": "2.10.0+cpu"
+  },
+  "model_type": "SentenceTransformer",
+  "prompts": {
+    "query": "",
+    "document": ""
+  },
+  "default_prompt_name": null,
+  "similarity_fn_name": "cosine"
+}