feat(ui): add global query refresh indicator to board header

Replace per-widget loading spinners with a shared header indicator that
shows live TanStack Query cache status for all widget-related queries.
Includes orange/green dot, completion beep, and hover card with
per-query staleness and error details.

apps/nextjs/src/components/layout/header/query-refresh-indicator.tsx

@@ -0,0 +1,218 @@
+"use client";
+
+import { useEffect, useRef, useState } from "react";
+import { Box, Group, HoverCard, Indicator, ScrollArea, Stack, Text } from "@mantine/core";
+import { IconDatabase } from "@tabler/icons-react";
+import { useQueryClient } from "@tanstack/react-query";
+import dayjs from "dayjs";
+
+import { HeaderButton } from "./button";
+
+interface QueryStatusRow {
+  id: string;
+  label: string;
+  status: "pending" | "error" | "success";
+  fetchStatus: "fetching" | "paused" | "idle";
+  dataUpdatedAt: number;
+  isStale: boolean;
+}
+
+const widgetQueryPrefixes = new Set(["widget", "docker", "app", "integration"]);
+
+const isWidgetQuery = (queryKey: readonly unknown[]): boolean => {
+  const first = queryKey[0];
+  return Array.isArray(first) && first.length >= 1 && widgetQueryPrefixes.has(first[0]);
+};
+
+const extractQueryLabel = (queryKey: readonly unknown[]): string => {
+  const first = queryKey[0];
+  if (Array.isArray(first)) {
+    return first.filter((s) => typeof s === "string").join(".");
+  }
+  return String(first);
+};
+
+const statusColorMap: Record<string, string> = {
+  fetching: "orange",
+  idle_success: "green",
+  idle_error: "red",
+  idle_pending: "gray",
+};
+
+interface CacheSnapshot {
+  rows: QueryStatusRow[];
+  widgetFetchingCount: number;
+  errorCount: number;
+  staleCount: number;
+}
+
+const emptyCacheSnapshot: CacheSnapshot = { rows: [], widgetFetchingCount: 0, errorCount: 0, staleCount: 0 };
+
+function useQueryCacheStatus() {
+  const queryClient = useQueryClient();
+  const [snapshot, setSnapshot] = useState<CacheSnapshot>(emptyCacheSnapshot);
+
+  useEffect(() => {
+    const update = () => {
+      const cache = queryClient.getQueryCache();
+      const queries = cache.findAll({ type: "active" }).filter((q) => isWidgetQuery(q.queryKey));
+
+      let fetching = 0;
+      let errors = 0;
+      let stale = 0;
+      const nextRows: QueryStatusRow[] = queries.map((q) => {
+        if (q.state.fetchStatus === "fetching") fetching++;
+        if (q.state.status === "error") errors++;
+        const isStale = q.isStale();
+        if (isStale) stale++;
+        return {
+          id: q.queryHash,
+          label: extractQueryLabel(q.queryKey),
+          status: q.state.status,
+          fetchStatus: q.state.fetchStatus,
+          dataUpdatedAt: q.state.dataUpdatedAt,
+          isStale,
+        };
+      });
+
+      setSnapshot({ rows: nextRows, widgetFetchingCount: fetching, errorCount: errors, staleCount: stale });
+    };
+
+    update();
+
+    let rafId: number | null = null;
+    const unsubscribe = queryClient.getQueryCache().subscribe(() => {
+      if (rafId !== null) return;
+      rafId = requestAnimationFrame(() => {
+        rafId = null;
+        update();
+      });
+    });
+
+    return () => {
+      unsubscribe();
+      if (rafId !== null) cancelAnimationFrame(rafId);
+    };
+  }, [queryClient]);
+
+  return { ...snapshot, totalCount: snapshot.rows.length };
+}
+
+const audioCtxRef = { current: null as AudioContext | null };
+
+function useCompletionBeep(fetchingCount: number) {
+  const prevRef = useRef(fetchingCount);
+
+  useEffect(() => {
+    const wasFetching = prevRef.current > 0;
+    const nowIdle = fetchingCount === 0;
+    prevRef.current = fetchingCount;
+
+    if (!wasFetching || !nowIdle) return;
+
+    try {
+      if (!audioCtxRef.current || audioCtxRef.current.state === "closed") {
+        audioCtxRef.current = new AudioContext();
+      }
+      const ctx = audioCtxRef.current;
+      const osc = ctx.createOscillator();
+      const gain = ctx.createGain();
+      osc.connect(gain);
+      gain.connect(ctx.destination);
+      osc.frequency.value = 880;
+      gain.gain.value = 0.08;
+      osc.start();
+      osc.stop(ctx.currentTime + 0.08);
+    } catch {
+      // audio blocked before user interaction
+    }
+  }, [fetchingCount]);
+}
+
+function useGreenFlash(fetchingCount: number) {
+  const [flash, setFlash] = useState(false);
+  const prevRef = useRef(fetchingCount);
+
+  useEffect(() => {
+    const wasFetching = prevRef.current > 0;
+    const nowIdle = fetchingCount === 0;
+    prevRef.current = fetchingCount;
+
+    if (!wasFetching || !nowIdle) return;
+
+    setFlash(true);
+    const timer = setTimeout(() => setFlash(false), 1500);
+    return () => clearTimeout(timer);
+  }, [fetchingCount]);
+
+  return flash;
+}
+
+export const QueryRefreshIndicator = () => {
+  const { rows, widgetFetchingCount, errorCount, staleCount, totalCount } = useQueryCacheStatus();
+  const showGreen = useGreenFlash(widgetFetchingCount);
+  useCompletionBeep(widgetFetchingCount);
+
+  if (totalCount === 0) return null;
+
+  const isFetching = widgetFetchingCount > 0;
+  const color = isFetching ? "orange" : showGreen ? "green" : errorCount > 0 ? "red" : "green";
+
+  return (
+    <HoverCard width={360} position="bottom-end" shadow="md" withArrow>
+      <HoverCard.Target>
+        <Indicator color={color} size={8} processing={isFetching} withBorder>
+          <HeaderButton>
+            <IconDatabase stroke={1.5} size={20} />
+          </HeaderButton>
+        </Indicator>
+      </HoverCard.Target>
+      <HoverCard.Dropdown>
+        <Stack gap="xs">
+          <Group justify="apart">
+            <Text size="sm" fw={600}>
+              Integration status
+            </Text>
+            <Text size="xs" c="dimmed">
+              {totalCount} queries &middot; {widgetFetchingCount} fetching, {staleCount} stale, {errorCount} errors
+            </Text>
+          </Group>
+
+          <ScrollArea.Autosize mah={240}>
+            <Stack gap={4}>
+              {rows.map((row) => (
+                <QueryRow key={row.id} row={row} />
+              ))}
+            </Stack>
+          </ScrollArea.Autosize>
+        </Stack>
+      </HoverCard.Dropdown>
+    </HoverCard>
+  );
+};
+
+const QueryRow = ({ row }: { row: QueryStatusRow }) => {
+  const rowColor = statusColorMap[
+    row.fetchStatus === "fetching" ? "fetching" : `idle_${row.status}`
+  ] ?? "gray";
+
+  const updatedLabel = row.dataUpdatedAt > 0
+    ? dayjs(row.dataUpdatedAt).fromNow()
+    : "never";
+
+  return (
+    <Group gap="xs" wrap="nowrap">
+      <Box
+        w={8}
+        h={8}
+        style={{ borderRadius: "50%", flexShrink: 0, backgroundColor: `var(--mantine-color-${rowColor}-6)` }}
+      />
+      <Text size="xs" lineClamp={1} style={{ flex: 1 }}>
+        {row.label}
+      </Text>
+      <Text size="xs" c="dimmed" style={{ flexShrink: 0 }}>
+        {updatedLabel}
+      </Text>
+    </Group>
+  );
+};