update: add YouTube video link

fix: restore YAML frontmatter to fix Space configuration error

docs: add Related Research section with sycophancy papers

docs: add Quick Links table to README

update: point to full trained model

update: complete README with results, API docs, reward curve

Update README: Phase 3 complete, HF Space badge, quickstart, reward table

Phase 3: Dockerfile, openenv manifest, client, deployment guide, GRPO training notebook

Phase 1 complete: schemas, reward design, project scaffold