md updates

docs: Day-8 close-out — AGENTS §12-§14 + README Day-8 row

docs(README): HF Spaces YAML + 5-sentence Executive Summary + Demo Scripts

docs: Day-7 close-out — AGENTS §10 drift + §11 LLM explainer + README recipe

docs: Day-6 close-out — AGENTS §8 calibration + §9 demo features

docs: Day-5 close-out — AGENTS §8 decision layer + trainer CLI

docs: Day-4 close-out — AGENTS §7 tracking, README MLOps surface

docs: fix README cross-references; type _StatFn as a real Callable alias

docs: mark MRI pipeline shipped; add Day-3 smoke run + function reference

refactor: pin single-threaded determinism env; close Day-2 doc/typo gaps

docs: mark EEG pipeline shipped; add Day-2 smoke run + function reference

docs: add README with quick start, status, and Day-2 onboarding map