Build or update the canonical raw bundle for a resolved paper under `~/papers/{title_slug}`. Use this skill whenever the user wants to download a paper PDF and normalize it into `paper.md`. For repository discovery, use `paper-repo` skill after this one. Prefer this skill for raw acquisition work; do not use it to write reading notes.
Hydrate the canonical raw bundle for a resolved paper.
This skill owns:
~/papers/{title_slug}/metadata.yaml (extends with assets, normalization)~/papers/{title_slug}/paper/paper.pdf~/papers/{title_slug}/paper/paper.md~/papers/{title_slug}/paper/paper_images/This skill does not:
paper-repo)identity or bibliography sections in metadata.yaml必须先有 metadata.yaml（由 paper-resolve 产出）。
如果用户只给了一个模糊引用，先用 paper-resolve。
读取 metadata.yaml，提取对 acquire 有用的信息：
# 从 metadata.yaml 提取