feat: 日报多来源入库（news_event.sources 列，JSON 数组，主源居首）

- EventRow 新增 sources 字段；init_schema 幂等 ALTER 补列（MariaDB）
- save_report 写入 sources JSON；_article_sources_full 完整来源列表
- source 字段保持 ≤3 拼接兼容；新增多源完整列表测试
- 已部署 pi5：sources 列写入验证通过（单源数组）；完整多源待新数据

report_db/db.py

@@ -113,12 +113,13 @@ def save_report(conn: pymysql.Connection, report: ReportData) -> int:
 
         cur.execute("DELETE FROM news_event WHERE report_id=%s", (report_id,))
         for ev in report.events:
+            sources_json = json.dumps(ev.sources, ensure_ascii=False) if ev.sources else None
             cur.execute(
                 """
                 INSERT INTO news_event
                     (report_id, section, rank, importance, event_type, title,
-                     summary, sentiment, source, url)
-                VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s)
+                     summary, sentiment, source, sources, url)
+                VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)
                 """,
                 (
                     report_id,
@@ -130,6 +131,7 @@ def save_report(conn: pymysql.Connection, report: ReportData) -> int:
                     ev.summary,
                     ev.sentiment,
                     ev.source,
+                    sources_json,
                     ev.url,
                 ),
             )