Add SKILL.md for lab homepage management #423

For papers, the skill file should lay out how venues are registered in index.md, the rules for papers (e.g., arXiv preprints get added without a PDF and then a new entry is added with the camera ready PDF once accepted somewhere), the available fields for a paper (e.g., links for homepage, code, data, pub categories and their definitions, awards), and important sanity checks (e.g., author list and abstract must be double checked closely by a human). This can be used to not only add papers with agents but also add AI-based reviewing for paper PRs.

Similar for awards and open source project pages.