fix: restore ChebNet's title from a field-config correction

[hedmana]

Closes #55

What

• corrected_titles in the field config maps OpenAlex ids to their true titles. Cleaning applies it, drops those records' abstracts, which came from the same wrong record, and counts them as retitled_nodes.
• gnn.yaml restores ChebNet's title on W2964321699.

Why

The UI showed ChebNet as "Advances In Deep Learning On Graphs (Gsp'18 Workshop)". Since #54, content weighting also read the record's lecture abstract as off-topic, which dropped ChebNet out of GCN's top six. After the correction, on the served snapshot:

learned ranking	dev found	dev Recall@10 / nDCG@10	test found	test Recall@10 / nDCG@10
before	23/32	0.903 / 0.717	17/31	0.626 / 0.556
after	24/32	0.931 / 0.756	17/31	0.626 / 0.561

It's a metadata fix, not tuning: the record was identified as wrong during the crawl expansion, before the gold set existed.

Verify

uv run pytest tests/test_build.py tests/test_config.py
uv run python -m graph.build --field gnn   # retitled_nodes 1

Generated with Claude Code