fix: COGS profit model - charge unit cost on sold units not on orders, preventing end-of-period bias against high-inventory strategies

fix: proxy HF Inference API through FastAPI to bypass HF Spaces CSP

metrics: profit first, then service level, then fill rate (React UI)

fix: add package-lock.json for npm ci in Docker build

feat: replace Gradio with React UI — GRPO tab, 730-day sim, 200-entry memory bank