feat: 日报事件多新闻源入库(news_event.sources 列)

- ExtractedEvent 增加 sources 字段(主源居首去重,旧产物兜底 [source_id])
- extract_event(_async) 增加 sources 参数;run_event_extraction 读取
  deduped uniques 的 sources 透传
- reporter _load_events_from_dir 读取 sources → EventRow.sources
- news_event 建表加 sources TEXT 列;init_schema 幂等迁移旧表(捕获
  Duplicate column);save_report INSERT 写 JSON 多源
- 新增测试:ExtractedEvent/EventRow.sources 兜底与保序、_load_events_from_dir 多源

scheduler/reporter.py

@@ -102,6 +102,7 @@ def _load_events_from_dir(day_str: str) -> list[dict]:
                 "title": obj.get("title", ""),
                 "url": obj.get("url", ""),
                 "source_id": obj.get("source_id", ""),
+                "sources": obj.get("sources") or [obj.get("source_id", "")],
                 "publish_time": obj.get("publish_time"),
                 "event": ev,
             })
@@ -1004,6 +1005,7 @@ def _build_report_data(news: dict, cninfo: dict, pipeline: dict,
                     summary=(ev.get("summary") or None),
                     sentiment=ev.get("sentiment") or None,
                     source=e.get("source_id") or None,
+                    sources=e.get("sources") or None,
                     url=e.get("url") or None,
                 )
             )