fix(cps): 时序分桶对 naive datetime 按 UTC 兜底(本地 SQLite 错桶)

clicked_at.astimezone 对 naive(SQLite 读回无 tz)会按系统时区解释→分桶偏移;
naive 先按 UTC 兜底再转北京,与 queries._as_utc 约定一致。生产 PG(tz-aware)本就正确。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/admin/repositories/cps.py

@@ -394,7 +394,10 @@ def group_click_timeseries(
 
     agg: dict = {}  # bucket_key -> {vp, vu(set), cp, cu(set)}
     for clicked_at, event_type, ip, ua in rows:
-        bj = clicked_at.astimezone(_BJ_TZ)
+        # naive(本地 SQLite 读回无 tz)按 UTC 兜底,再转北京——与 queries._as_utc 约定一致,
+        # 否则 astimezone 会把 UTC 瞬刻当系统本地时区解释,分桶整体偏移。
+        ca = clicked_at if clicked_at.tzinfo else clicked_at.replace(tzinfo=timezone.utc)
+        bj = ca.astimezone(_BJ_TZ)
         key = bj.strftime("%Y-%m-%d") if granularity == "day" else bj.hour
         b = agg.setdefault(key, {"vp": 0, "vu": set(), "cp": 0, "cu": set()})
         uid = f"{ip or ''}|{ua or ''}"