fix(admin): 仪表盘读不到数据时不再画成 0/「全部在线」

与渠道页同一类误导（主人本次误读的同源问题）：六个 HTTP 卡片（人格/会话/记忆/插件/渠道/IoT）原用 `data ?? []` + `?? 0`，后端不可达时显示 0 且「全部在线」（tone=ok），把「读不到」画成好消息。
- 改为复用 channels/channelStatus 的列表三态：unknown → 「—」+「读取失败（与后端失联）」(warn)；pending → 「—」+「读取中…」(neutral)
- WS 驱动的 Agent / 后台思考卡片不依赖 HTTP，保持不变
- 验收：npm run build 绿 + channelStatus 45 断言 + messageSync 54 断言回归

frontend/web/src/admin/modules/Dashboard.tsx

@@ -14,6 +14,7 @@ import { Tag } from "../../components/primitives";
 import { Icon, type IconName } from "../../components/Icon";
 import { useAutoReload } from "../hooks";
 import { OverviewSection } from "./dashboard/OverviewSection";
+import { channelListState } from "./channels/channelStatus";
 
 interface DashCard {
   id: AdminSectionId;
@@ -43,25 +44,58 @@ export function DashboardModule(): React.ReactNode {
   const backthink = useAppStore((s) => s.backthink);
   const wsStatus = useAppStore((s) => s.wsStatus);
 
-  const nPersonas = personas.data?.length ?? 0;
-  const nSessions = sessions.data?.length ?? 0;
-  const nMemories = memories.data?.length ?? 0;
-  const nPlugins = plugins.data?.length ?? 0;
-  const nChannels = channels.data?.length ?? 0;
-  const nDevices = iot.data?.length ?? 0;
-  const offlineChannels = (channels.data ?? []).filter((c) => !c.connected).length;
-  const onlineDevices = (iot.data ?? []).filter((d) => d.online).length;
   const runningAgents = agents.filter((a) => a.status === "running").length;
 
+  type Stat = { value: number | string; sub: string; tone: DashCard["tone"] };
+  /** One HTTP-backed stat card. A list we could not read is "unknown" (—), never a
+   *  fabricated 0 / 「全部在线」: the dashboard is the first thing the owner opens
+   *  when something feels wrong, so it must not turn a dead backend into good news.
+   *  Reuses the channel pages' list tri-state so the rule stays in one place. */
+  const stat = <T,>(
+    req: { data: readonly T[] | null; error: string | null },
+    ready: (list: readonly T[]) => Stat,
+  ): Stat => {
+    switch (channelListState(req.data, req.error)) {
+      case "unknown":
+        return { value: "—", sub: "读取失败（与后端失联）", tone: "warn" };
+      case "pending":
+        return { value: "—", sub: "读取中…", tone: "neutral" };
+      default:
+        return ready(req.data as readonly T[]);
+    }
+  };
+
   const cards: DashCard[] = [
-    { id: "personas", label: "人格", icon: "dna", value: nPersonas, sub: "启停/默认/路由", tone: "accent" },
-    { id: "sessions", label: "活跃会话", icon: "chat", value: nSessions, sub: "渠道 × actor", tone: "ok" },
-    { id: "memories", label: "记忆", icon: "memory", value: nMemories, sub: "三类作用域隔离", tone: "accent" },
-    { id: "plugins", label: "插件与能力", icon: "plugin", value: nPlugins, sub: "含 MCP/渠道", tone: "neutral" },
-    { id: "channels", label: "渠道", icon: "channel", value: `${nChannels - offlineChannels}/${nChannels}`,
-      sub: offlineChannels > 0 ? `${offlineChannels} 离线` : "全部在线", tone: offlineChannels > 0 ? "warn" : "ok" },
-    { id: "iot", label: "IoT 设备", icon: "device", value: `${onlineDevices}/${nDevices}`,
-      sub: onlineDevices === nDevices && nDevices > 0 ? "全部在线" : "设备状态", tone: nDevices > 0 && onlineDevices === nDevices ? "ok" : "neutral" },
+    { id: "personas", label: "人格", icon: "dna", ...stat(personas, (l) => ({ value: l.length, sub: "启停/默认/路由", tone: "accent" })) },
+    { id: "sessions", label: "活跃会话", icon: "chat", ...stat(sessions, (l) => ({ value: l.length, sub: "渠道 × actor", tone: "ok" })) },
+    { id: "memories", label: "记忆", icon: "memory", ...stat(memories, (l) => ({ value: l.length, sub: "三类作用域隔离", tone: "accent" })) },
+    { id: "plugins", label: "插件与能力", icon: "plugin", ...stat(plugins, (l) => ({ value: l.length, sub: "含 MCP/渠道", tone: "neutral" })) },
+    {
+      id: "channels",
+      label: "渠道",
+      icon: "channel",
+      ...stat(channels, (l) => {
+        const offline = l.filter((c) => !c.connected).length;
+        return {
+          value: `${l.length - offline}/${l.length}`,
+          sub: offline > 0 ? `${offline} 离线` : "全部在线",
+          tone: offline > 0 ? "warn" : "ok",
+        };
+      }),
+    },
+    {
+      id: "iot",
+      label: "IoT 设备",
+      icon: "device",
+      ...stat(iot, (l) => {
+        const online = l.filter((d) => d.online).length;
+        return {
+          value: `${online}/${l.length}`,
+          sub: online === l.length && l.length > 0 ? "全部在线" : "设备状态",
+          tone: l.length > 0 && online === l.length ? "ok" : "neutral",
+        };
+      }),
+    },
     { id: "agents", label: "Agent 运行", icon: "agent", value: runningAgents, sub: `${agents.length} 个已登记`, tone: runningAgents > 0 ? "accent" : "neutral" },
     { id: "backthink", label: "后台思考活跃度", icon: "night", value: backthink.length, sub: "实时 (WS)", tone: backthink.length > 0 ? "warn" : "neutral" },
   ];