feat(HEL-382): 搭建 datahub 底座和盘后正式数据链路

新增独立 xiaobai-datahub 服务（SQLite WAL、Tushare 盘后发布、/v1 契约和管理后台），不改现站页面与数据链路。

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

xiaobai-datahub/datahub/timeutil.py

@@ -0,0 +1,64 @@
+from __future__ import annotations
+
+from datetime import date, datetime, time, timedelta, timezone
+from typing import Any
+from zoneinfo import ZoneInfo
+
+SHANGHAI = ZoneInfo("Asia/Shanghai")
+
+
+def now_shanghai(clock: datetime | None = None) -> datetime:
+    if clock is not None:
+        if clock.tzinfo is None:
+            return clock.replace(tzinfo=SHANGHAI)
+        return clock.astimezone(SHANGHAI)
+    return datetime.now(SHANGHAI)
+
+
+def isoformat(value: datetime | None = None) -> str:
+    current = now_shanghai(value)
+    return current.isoformat(timespec="seconds")
+
+
+def yyyymmdd(value: date | datetime | str | None = None) -> str:
+    if value is None:
+        return now_shanghai().strftime("%Y%m%d")
+    if isinstance(value, str):
+        digits = value.replace("-", "")[:8]
+        if len(digits) != 8 or not digits.isdigit():
+            raise ValueError(f"invalid trade_date: {value}")
+        return digits
+    if isinstance(value, datetime):
+        return value.astimezone(SHANGHAI).strftime("%Y%m%d")
+    return value.strftime("%Y%m%d")
+
+
+def parse_trade_date(value: str) -> date:
+    text = yyyymmdd(value)
+    return date(int(text[:4]), int(text[4:6]), int(text[6:8]))
+
+
+def session_phase(clock: datetime | None, is_open_day: bool) -> str:
+    """pre | intradaily | lunch | eod | closed"""
+    if not is_open_day:
+        return "closed"
+    current = now_shanghai(clock).time()
+    if current < time(9, 15):
+        return "pre"
+    if current < time(11, 30) or (time(13, 0) <= current <= time(15, 5)):
+        return "intraday"
+    if current < time(13, 0):
+        return "lunch"
+    if current <= time(23, 40):
+        return "eod"
+    return "closed"
+
+
+def add_days(trade_date: str, days: int) -> str:
+    return (parse_trade_date(trade_date) + timedelta(days=days)).strftime("%Y%m%d")
+
+
+def utc_timestamp(value: Any) -> str:
+    if isinstance(value, datetime):
+        return isoformat(value)
+    return isoformat()