feat: add settings and async db engine

backend/tests/conftest.py

@@ -0,0 +1,8 @@
+import os
+
+
+def pytest_configure(config):
+    """Set up minimal environment variables for tests before any imports."""
+    os.environ.setdefault("DATABASE_URL", "postgresql+asyncpg://test:test@localhost/test")
+    os.environ.setdefault("OLLAMA_BASE_URL", "http://localhost:11434")
+    os.environ.setdefault("SESSION_SECRET", "test-secret-key")