Bibliography (#229)

* update bibliography

* bibliography: add Zotero-only papers and Crossref DOIs

Add seven papers from the Zotero SU2 group that were missing from SU2.bib
and add DOIs to 66 entries that had none (Crossref title match >= 0.95,
year within one).

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

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Co-authored-by: Claude Sonnet 5.5 <noreply@anthropic.com>

Author: bigfooted