fix(HEL-190): 按真实交易日历补齐最近60日快照，修复断档后只显示当天

保留连续性过滤，新增可审计补档工具与备份步骤；周末/节假日与真缺档分开处理，支持重复执行与部分失败续跑。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

frontend/shared/admin.js

@@ -7,7 +7,14 @@ async function backfillData() {
       start_date: document.querySelector("#backfillStart").value,
       end_date: document.querySelector("#backfillEnd").value,
     });
-    showToast(`历史回补完成，共处理 ${payload.results.length} 个工作日`);
+    const failed = (payload.failed_count || 0);
+    const skipped = (payload.skipped_non_trading_days || []).length;
+    const suffix = failed
+      ? `，失败 ${failed} 个`
+      : skipped
+        ? `，跳过 ${skipped} 个非交易日`
+        : "";
+    showToast(`历史回补完成，共处理 ${payload.results.length} 个交易日${suffix}`);
     state.sentimentHistory = null;
     state.sentimentHistoryKey = "";
     if (state.activeView === "sentimentCycleView") {