清理市场概览残留：删除 MarketOverviewBanner+refresh_policy 中的 marketOverview 条目

src/utils/refresh_policy.py

@@ -0,0 +1,9 @@
+"""Shared refresh cadence policy for the web terminal and data collectors."""
+
+from __future__ import annotations
+
+OBSERVATION_REFRESH_SEC = 60
+METAR_POLL_TTL_SEC = 5 * 60
+SCAN_ROWS_REFRESH_SEC = 5 * 60
+MODEL_CACHE_TTL_SEC = 30 * 60
+