fix(HEL-412): 刷新降级不再整次失败，并补齐准备中提示

手动刷新与自动补跑共用可用数据判定：日线推算或上一交易日快照记为部分/准备中成功，避免前端误报刷新失败。HTTP JSON 解析错误不再把请求正文写入日志。

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

frontend/m/js/pages.js

@@ -770,11 +770,33 @@
     scroll.classList.add("m-motion-fade-in");
   }
 
+  function dashboardFreshnessNotice() {
+    const meta = (state.dashboard && state.dashboard.meta) || {};
+    if (meta.display_notice) return String(meta.display_notice);
+    const requested = String(meta.requested_date || "").replace(/-/g, "");
+    const actual = String(meta.trade_date || "").replace(/-/g, "");
+    const compact = actual;
+    const shown = /^\d{8}$/.test(compact)
+      ? (Number(compact.slice(4, 6)) + " 月 " + Number(compact.slice(6, 8)) + " 日")
+      : "";
+    if (meta.data_status === "preparing" || (meta.carried_forward && actual && requested && actual !== requested)) {
+      return shown ? ("今日数据正在准备，当前展示 " + shown) : "今日数据正在准备，当前展示最近可用数据";
+    }
+    if (meta.data_status === "partial" || meta.limit_data_source === "derived") {
+      return meta.notice || "部分正式数据尚未到齐，当前展示日线推算结果";
+    }
+    return "";
+  }
+
   function renderTopArea(key) {
     const page = document.querySelector(".m-page");
     if (!page) return;
     let top = page.querySelector(".m-top");
     let html = buildStrip();
+    const freshness = dashboardFreshnessNotice();
+    if (freshness) {
+      html = '<div class="m-phase-notice"><strong>' + escapeHtml(freshness) + "</strong></div>" + html;
+    }
     if (key === "market/performance") html += performanceConclusion();
     if (!top) {
       top = document.createElement("div");