Dockerize chat_backend + Ollama LAN + DB file storage (#6) (#7)

## Summary

Implements [chat_backend#6](#6) Part A:

- **uv** packaging (`pyproject.toml` + `uv.lock`), Docker/compose (dev + prod), entrypoint/validate-env, Gitea unit-test + auto-deploy workflows (mirror `scha`)
- Env-driven Django settings (`DJANGO_*`, `DATABASE_URL`, CSRF/CORS)
- **`OLLAMA_BASE_URL`** wired through all Ollama/LangChain clients (prod → `http://10.0.0.128:11434`)
- **DatabaseStorage** — prompt/document file blobs in Postgres (`StoredFile`), not container FS; RAG materializes temp paths for loaders
- ASGI via `gunicorn` + `UvicornWorker` (HTTP + WebSockets)

Companion server-infra PR registers `app_catalog` / `host_apps` (port **8003**).

## Test plan

- [ ] `uv sync && cd llm_be && SKIP_RAG_INIT=1 uv run python manage.py test`
- [ ] `docker compose build && docker compose up` against bundled Postgres
- [ ] Confirm Ollama calls use `OLLAMA_BASE_URL` (not hardcoded localhost)
- [ ] Upload a document / prompt file → row in `chat_backend_storedfile`, no disk under `media/`
- [ ] After server-infra merge + secret/Postgres/NPM: deploy via `deploy.sh --app chat_backend --env prod`Reviewed-on: #7

pyproject.toml

@@ -0,0 +1,52 @@
+[project]
+name = "chat-backend"
+version = "0.1.0"
+description = "Django chat backend for AIML Operations"
+readme = "README.md"
+requires-python = ">=3.12"
+dependencies = [
+    "Django==6.0",
+    "channels==4.3.2",
+    "daphne==4.2.1",
+    "uvicorn==0.38.0",
+    "gunicorn==23.0.0",
+    "psycopg2-binary==2.9.10",
+    "whitenoise==6.9.0",
+    "djangorestframework==3.16.1",
+    "djangorestframework-simplejwt==5.5.1",
+    "django-cors-headers==4.9.0",
+    "django-autoslug==1.9.9",
+    "django-filter==25.2",
+    "ollama==0.6.1",
+    "langchain==1.1.2",
+    "langchain-core==1.1.1",
+    "langchain-community==0.4.1",
+    "langchain-classic==1.0.0",
+    "langchain-ollama==1.0.0",
+    "langchain-chroma==1.0.0",
+    "langchain-text-splitters==1.0.0",
+    "chromadb==1.3.5",
+    "unstructured==0.18.21",
+    "pypdf==6.4.0",
+    "python-docx==1.2.0",
+    "docx2txt==0.8",
+    "openpyxl==3.1.5",
+    "pandas==2.3.3",
+    "numpy==2.2.6",
+    "matplotlib==3.10.7",
+    "pillow==12.0.0",
+    "beautifulsoup4==4.14.3",
+    "ddgs==9.9.3",
+    "httpx==0.28.1",
+    "python-dateutil==2.9.0.post0",
+    "pytz==2025.2",
+]
+
+[dependency-groups]
+dev = [
+    "parameterized==0.9.0",
+    "black==25.11.0",
+]
+
+[tool.uv]
+package = false