Add OpenAICompatAdapter that works with any OpenAI-compatible API endpoint
(OpenWebUI, vLLM, Ollama, OpenAI, Anthropic via proxy). Features:
- Async HTTP calls via httpx with configurable timeout
- Chat completions format with system + user messages
- Token usage parsing from responses
- Exponential backoff retries (configurable, default 3 attempts)
- Both streaming (SSE) and non-streaming modes
- Model listing and connection testing
- 21 tests covering construction, request building, response parsing,
retry logic, and error handling
Define the LLM adapter interface in backend/engine/adapters/base.py with
async methods complete(), list_models(), and test_connection(). The
AdapterResponse dataclass holds response text, token counts, latency,
model name, and raw metadata. Includes 11 tests covering instantiation
guards, concrete subclass behavior, and dataclass semantics.
Set up all directories from the spec's Project Structure section:
- backend/ with routers/, engine/adapters/, engine/scorers/, mcp/,
websocket/, tests/ (all with __init__.py)
- frontend/src/ with pages/, components/, api/ (.gitkeep)
- docker/ (.gitkeep)
- alembic/versions/ (.gitkeep)
