feat(app): add POST /grade endpoint with active-episode guard and programmatic grader

feat(app): add GET /history endpoint — returns full attack_history list

feat(app): add GET /state endpoint — returns current EpisodeState snapshot

feat(app): add POST /step endpoint — executes one attack turn, returns StepResult

feat(app): add POST /reset endpoint — starts new episode, returns ResetResponse

feat(app): add GET /health endpoint for HuggingFace Spaces liveness probe

feat(app): wire RewardComputer and run_llm_pipeline into environment on startup

feat(app): add lifespan hook — creates RedTeamEnvironment on startup

feat(app): add CORS middleware — allow all origins for Spaces compatibility

feat(app): scaffold FastAPI app with title, version and lifespan hook