fix: harden DB session handling and ArXiv journal_ref forwarding (Round 3)

- Wrap __save_journal_to_db in try/except to handle DB session failures
  gracefully (e.g., encrypted DB with wrong password). Score is still
  valid but won't be cached until next successful DB access.
- Explicitly forward journal_ref in ArXiv _get_full_content to prevent
  fragile reliance on item.copy() preserving the field.

src/local_deep_research/advanced_search_system/filters/journal_reputation_filter.py

@@ -660,6 +660,52 @@ JOURNAL INFORMATION:
         if session_ctx is None:
             # No thread context (preview filter phase) — skip DB save
             return
+        try:
+            self._save_journal_to_db_inner(
+                session_ctx,
+                name=name,
+                quality=quality,
+                score_source=score_source,
+                h_index=h_index,
+                impact_factor=impact_factor,
+                sjr_quartile=sjr_quartile,
+                is_in_doaj=is_in_doaj,
+                has_doaj_seal=has_doaj_seal,
+                is_predatory=is_predatory,
+                predatory_source=predatory_source,
+                issn=issn,
+                publisher=publisher,
+                openalex_source_id=openalex_source_id,
+                source_type=source_type,
+                is_indexed_in_scopus=is_indexed_in_scopus,
+            )
+        except Exception:
+            logger.warning(
+                f"Failed to save journal '{name}' to DB — "
+                f"score is still valid but won't be cached."
+            )
+
+    def _save_journal_to_db_inner(
+        self,
+        session_ctx,
+        *,
+        name: str,
+        quality: int,
+        score_source: str,
+        h_index: int | None = None,
+        impact_factor: float | None = None,
+        sjr_quartile: str | None = None,
+        is_in_doaj: bool | None = None,
+        has_doaj_seal: bool | None = None,
+        is_predatory: bool | None = None,
+        predatory_source: str | None = None,
+        issn: str | None = None,
+        publisher: str | None = None,
+        openalex_source_id: str | None = None,
+        source_type: str | None = None,
+        is_indexed_in_scopus: bool | None = None,
+    ) -> None:
+        """Inner save logic, separated to wrap DB session errors cleanly."""
         with session_ctx as db_session:
             journal = db_session.query(Journal).filter_by(name=name).first()
             now = int(time.time())

src/local_deep_research/web_search_engines/engines/search_engine_arxiv.py

@@ -251,6 +251,8 @@ class ArXivSearchEngine(BaseSearchEngine):
                         "summary": paper.summary,  # Full summary
                         "comment": paper.comment,
                         "doi": paper.doi,
+                        # Explicitly forward for journal quality filter
+                        "journal_ref": paper.journal_ref,
                     }
                 )