feat: add functional Ollama chat tests with containerised LLM

Add an ollama service (behind --profile ollama) to the test compose stack
and a new test suite that verifies real LLM inference end-to-end:

- docker-compose.test.yml: add ollama/ollama service with health check,
  make OLLAMA_URL and OLLAMA_MODEL configurable via env vars
- tests/functional/test_ollama_chat.py: session-scoped fixture that
  brings up Ollama + dashboard, pulls qwen2.5:0.5b (~400MB, CPU-only),
  and runs chat/history/multi-turn tests against the live stack
- Makefile: add `make test-ollama` target

Run with: make test-ollama (or FUNCTIONAL_DOCKER=1 pytest tests/functional/test_ollama_chat.py -v)

https://claude.ai/code/session_01NTEzfRHSZQCfkfypxgyHKk

Makefile

@@ -62,6 +62,12 @@ test-cov-html:
 	$(PYTEST) tests/ --cov=src --cov-report=term-missing --cov-report=html -q
 	@echo "✓ HTML coverage report: open htmlcov/index.html"
 
+# Full-stack functional test: spins up Ollama (CPU, qwen2.5:0.5b) + dashboard
+# in Docker and verifies real LLM chat end-to-end.
+# Override model: make test-ollama OLLAMA_TEST_MODEL=tinyllama
+test-ollama:
+	FUNCTIONAL_DOCKER=1 $(PYTEST) tests/functional/test_ollama_chat.py -v --tb=long -x
+
 # ── Code quality ──────────────────────────────────────────────────────────────
 
 lint: