style: ruff format normalization to line-length=100

Committed code predated the line-length=100 ruff config; this brings the
five drifted files into compliance. No logic change.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

codex/sources/semanticscholar.py

@@ -96,10 +96,7 @@ def fetch_references(paper_id: str) -> list[Citation]:
         context: str | None = contexts[0] if contexts else None
 
         cited_id: str = (
-            external_ids.get("DOI")
-            or external_ids.get("ArXiv")
-            or cited_paper.get("paperId")
-            or ""
+            external_ids.get("DOI") or external_ids.get("ArXiv") or cited_paper.get("paperId") or ""
         )
         if cited_id:
             citations.append(Citation(citing_id=paper_id, cited_id=cited_id, context=context))