feat: expose explicit source conflicts

apps/api/app/activity.py

@@ -80,6 +80,7 @@ def activity_rows(
             sources=coordinate_sources,
             coordinate_precision=coordinate_precision,
             coordinate_sources=coordinate_sources,
+            source_conflicts=_source_conflicts(items),
         ))
     return sorted(result, key=lambda row: (row.activity_score, row.last_confirmed_at), reverse=True)
 
@@ -95,6 +96,16 @@ def _source_system(report: CatchReport) -> str:
     return "manual-import"
 
 
+def _source_conflicts(reports: list[CatchReport]) -> list[str]:
+    conflicts: set[str] = set()
+    for report in reports:
+        provenance = (report.raw_payload or {}).get("provenance", {})
+        values = provenance.get("conflicts", []) if isinstance(provenance, dict) else []
+        if isinstance(values, list):
+            conflicts.update(str(value).strip() for value in values if str(value).strip())
+    return sorted(conflicts)
+
+
 def _coordinate_precision(report: CatchReport) -> str:
     provenance = (report.raw_payload or {}).get("provenance", {})
     value = provenance.get("coordinate_precision") if isinstance(provenance, dict) else None