feat(HEL-421): 回补历史日历和指数并标记区间不完整

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

xiaobai-datahub/datahub/timeutil.py

@@ -58,6 +58,16 @@ def add_days(trade_date: str, days: int) -> str:
     return (parse_trade_date(trade_date) + timedelta(days=days)).strftime("%Y%m%d")
 
 
+def iter_yyyymmdd(start: str, end: str):
+    cursor = parse_trade_date(start)
+    last = parse_trade_date(end)
+    if cursor > last:
+        return
+    while cursor <= last:
+        yield cursor.strftime("%Y%m%d")
+        cursor += timedelta(days=1)
+
+
 def utc_timestamp(value: Any) -> str:
     if isinstance(value, datetime):
         return isoformat(value)