Dockerize chat_backend for server-infra deploy (closes #6).

Add uv packaging, env-driven Django settings, OLLAMA_BASE_URL (LAN GPU
host), DatabaseStorage for prompt/document blobs, compose/CI/deploy
workflows mirroring scha, and ASGI gunicorn+UvicornWorker for WebSockets.

.gitea/workflows/unittests.yml

@@ -0,0 +1,35 @@
+name: Unit Tests
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  test:
+    runs-on: self-hosted
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install uv
+        run: |
+          curl -LsSf https://astral.sh/uv/install.sh | sh
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+
+      - name: Install dependencies
+        run: uv sync --frozen
+
+      - name: Run unit tests
+        env:
+          DJANGO_ENV: dev
+          DJANGO_SECRET_KEY: test-secret-key
+          DJANGO_DEBUG: "true"
+          DJANGO_ALLOWED_HOSTS: localhost,127.0.0.1,testserver
+          DATABASE_URL: ""
+          DB_HOST: ""
+          SKIP_RAG_INIT: "1"
+          OLLAMA_BASE_URL: http://127.0.0.1:11434
+        working-directory: llm_be
+        run: uv run python manage.py test