fix(ai): subject 里塞了行数，每轮询一次就新建一个任务

生产上 trends 队列里积了 36 个任务，subject 是 2026-09-01:1033、:1039、
:1044……一路涨。这台账号当时正在补历史，get_summary 的行数每隔几分钟就变，
而我把 len(rows) 写进了 subject——subject 同时是缓存键和任务队列的键，一变
就是一条全新的任务，轮询几次就刷出十几条。

subject 该回答的是「这条解读是关于什么的」，不是「当时有多少行数据」。
数据变化本来就由 fingerprint 负责。

- trends 的 subject 改成快照日期；sleep 用配置的窗口常量而不是实际夜数
  （缺一晚也不该换键）；challenges 用固定键
- 加了不变量测试：补一天历史数据后 subject 不许变；任何 subject 段都不许
  长得像行数

顺带加一层兜底 jobs.supersede()：单实例 scope 只该有一个在跑的 subject，
队列里同 kind 的其它 pending 任务是关于已经不存在的快照的，跑完也没人看。
per_item 的 daily / activity 不受影响——它们本来就一天一条、一次运动一条。
兜底不是机制，机制是 subject 稳定；它存在只是因为这次 subject 不稳定，而
36 条任务堆在那里之前没人发现。

顺带按要求把 AiPanel 改成默认精简：只显示标题、来源和一句话结论，点「展开
详细」才出要点/建议/依据，可再收起——和今日晨报卡片一致。这些面板压在本来
就很密的图表页上面，全部默认展开会把真正的数据一次性挤到屏幕外。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

client/src/components/AiPanel.css

@@ -85,6 +85,36 @@
   color: var(--text-primary);
 }
 
+.aip-detail {
+  border-top: 1px solid var(--border);
+  padding-top: 0.7rem;
+  margin-top: 0.5rem;
+  animation: aip-open 0.26s var(--ease) both;
+}
+
+@keyframes aip-open {
+  from { opacity: 0; transform: translateY(-4px); }
+  to { opacity: 1; transform: none; }
+}
+
+/* Full-width, at the foot of the card: the same affordance the 今日 briefing
+   uses, so the two read as one pattern rather than two. */
+.aip-toggle {
+  display: block;
+  width: 100%;
+  background: none;
+  border: none;
+  border-top: 1px solid var(--border);
+  margin-top: 0.5rem;
+  padding: 0.5rem 0 0.1rem;
+  font-size: 0.76rem;
+  font-weight: 600;
+  color: var(--text-muted);
+  cursor: pointer;
+}
+
+.aip-toggle:active { color: var(--accent); }
+
 .aip-point { margin-bottom: 0.55rem; }
 
 .aip-tag {

client/src/components/AiPanel.tsx

@@ -1,4 +1,4 @@
-import { useCallback } from 'react';
+import { useCallback, useState } from 'react';
 import {
   apiClient, InsightScope, InsightMeta, ScopeInsight,
 } from '../services/api';
@@ -48,6 +48,13 @@ function Badge({ meta }: { meta: InsightMeta }) {
  * screen — which opening the screen moves to the front of.
  */
 function AiPanel({ scope, subject, title = 'AI 解读' }: Props) {
+  /* Collapsed by default, the same as the 今日 briefing card. These panels sit
+     on top of screens that are already dense with charts; opening every one of
+     them by default would push the actual data below the fold on every screen
+     at once. The conclusion is always visible — it is the detail behind it
+     that waits to be asked for. */
+  const [open, setOpen] = useState(false);
+
   const load = useCallback(async () => {
     const resp = await apiClient.getInsight(scope, { subject });
     return { data: resp.insight, meta: resp.meta };
@@ -71,27 +78,42 @@ function AiPanel({ scope, subject, title = 'AI 解读' }: Props) {
 
       {data.headline && <p className="aip-headline">{data.headline}</p>}
 
-      {data.points.map((p) => (
-        <div className="aip-point" key={p.title + p.detail}>
-          <span className="aip-tag">{p.title}</span>
-          <p>{p.detail}</p>
-        </div>
-      ))}
+      {open && (
+        <div className="aip-detail">
+          {data.points.map((p) => (
+            <div className="aip-point" key={p.title + p.detail}>
+              <span className="aip-tag">{p.title}</span>
+              <p>{p.detail}</p>
+            </div>
+          ))}
 
-      {!!data.actions.length && (
-        <ul className="aip-actions">
-          {data.actions.map((a) => <li key={a}>{a}</li>)}
-        </ul>
+          {!!data.actions.length && (
+            <ul className="aip-actions">
+              {data.actions.map((a) => <li key={a}>{a}</li>)}
+            </ul>
+          )}
+
+          {data.caution && <p className="aip-caution">{data.caution}</p>}
+
+          <div className="aip-foot">
+            <button className="aip-link" onClick={refresh} disabled={loading}>
+              {loading ? '重新生成中…' : '重新生成'}
+            </button>
+            <span>{CONFIDENCE_LABEL[data.confidence]}</span>
+          </div>
+        </div>
       )}
 
-      {data.caution && <p className="aip-caution">{data.caution}</p>}
-
-      <div className="aip-foot">
-        <button className="aip-link" onClick={refresh} disabled={loading}>
-          {loading ? '重新生成中…' : '重新生成'}
+      {/* Nothing to expand into when the reading is a headline on its own. */}
+      {(!!data.points.length || !!data.actions.length || !!data.caution) && (
+        <button
+          className="aip-toggle"
+          onClick={() => setOpen((v) => !v)}
+          aria-expanded={open}
+        >
+          {open ? '收起' : `展开详细（${data.points.length} 项）`}
         </button>
-        <span>{CONFIDENCE_LABEL[data.confidence]}</span>
-      </div>
+      )}
     </section>
   );
 }