Add system alerts log with nav badge and Admin Alerts tab.

Persist job and ingestion warnings/errors for 7 days, surface a dismissible top-nav badge, treat stale OHLCV as a warning (e.g. ticker renames), and show market bar age on the ticker freshness chip.

frontend/src/components/layout/TopBar.tsx

@@ -1,9 +1,11 @@
+import { useState } from 'react';
 import { NavLink } from 'react-router-dom';
 import { useQuery } from '@tanstack/react-query';
 import { useAuthStore } from '../../stores/authStore';
 import { check as healthCheck } from '../../api/health';
 import { getRunningJobs } from '../../api/jobs';
 import { useMarketRegime } from '../../hooks/useMarketRegime';
+import { useSystemEventSummary, useAcknowledgeSystemEvents } from '../../hooks/useAdmin';
 import { regimeDot, regimeHeadline } from '../../lib/regime';
 import TickerSearch from './TickerSearch';
 
@@ -24,6 +26,7 @@ const linkClasses = (isActive: boolean) =>
 /** Desktop command bar — the mockup's top navigation. MobileNav covers <lg. */
 export default function TopBar() {
   const { role, username, logout } = useAuthStore();
+  const [alertsOpen, setAlertsOpen] = useState(false);
 
   const health = useQuery({
     queryKey: ['health'],
@@ -42,6 +45,11 @@ export default function TopBar() {
     enabled: isBackendUp,
   });
 
+  const eventSummary = useSystemEventSummary(7);
+  const ackEvents = useAcknowledgeSystemEvents();
+  const unacked = eventSummary.data?.unacknowledged ?? 0;
+  const unackedErrors = eventSummary.data?.unacknowledged_errors ?? 0;
+
   const running = jobs.data?.running ?? [];
   const regime = useMarketRegime();
 
@@ -108,6 +116,85 @@ export default function TopBar() {
             </span>
           </span>
         )}
+
+        {/* System alerts badge — open issues from jobs / ingestion */}
+        <div className="relative">
+          <button
+            type="button"
+            onClick={() => setAlertsOpen((v) => !v)}
+            className={`relative flex items-center gap-1.5 rounded-md px-1.5 py-1 text-[11px] transition-colors ${
+              unacked > 0
+                ? unackedErrors > 0
+                  ? 'text-red-300 hover:bg-red-500/10'
+                  : 'text-amber-300 hover:bg-amber-500/10'
+                : 'text-gray-500 hover:bg-white/[0.04] hover:text-gray-300'
+            }`}
+            title={unacked > 0 ? `${unacked} open system alert${unacked === 1 ? '' : 's'}` : 'No open system alerts'}
+            aria-label={unacked > 0 ? `${unacked} open system alerts` : 'System alerts'}
+            aria-expanded={alertsOpen}
+          >
+            <svg className="h-4 w-4" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth={1.75}>
+              <path strokeLinecap="round" strokeLinejoin="round" d="M15 17h5l-1.4-1.4A2 2 0 0118 14.2V11a6 6 0 10-12 0v3.2c0 .5-.2 1-.6 1.4L4 17h5m6 0v1a3 3 0 11-6 0v-1m6 0H9" />
+            </svg>
+            {unacked > 0 && (
+              <span className={`num min-w-[1.1rem] rounded-full px-1 text-center text-[10px] font-semibold ${
+                unackedErrors > 0 ? 'bg-red-500/25 text-red-200' : 'bg-amber-500/25 text-amber-100'
+              }`}>
+                {unacked > 99 ? '99+' : unacked}
+              </span>
+            )}
+          </button>
+          {alertsOpen && (
+            <>
+              <button
+                type="button"
+                className="fixed inset-0 z-40 cursor-default"
+                aria-label="Close alerts"
+                onClick={() => setAlertsOpen(false)}
+              />
+              <div className="absolute right-0 top-full z-50 mt-2 w-72 rounded-xl border border-white/[0.08] bg-[#12141c] p-3 shadow-xl">
+                <p className="text-[11px] font-medium text-gray-300">
+                  {unacked > 0
+                    ? `${unacked} open alert${unacked === 1 ? '' : 's'} (last 7 days)`
+                    : 'No open alerts'}
+                </p>
+                {eventSummary.data && eventSummary.data.total > 0 && (
+                  <p className="mt-0.5 text-[10px] text-gray-500">
+                    {eventSummary.data.unacknowledged_errors} error
+                    {eventSummary.data.unacknowledged_errors === 1 ? '' : 's'}
+                    {' · '}
+                    {eventSummary.data.unacknowledged_warnings} warning
+                    {eventSummary.data.unacknowledged_warnings === 1 ? '' : 's'} open
+                  </p>
+                )}
+                <div className="mt-3 flex flex-col gap-1.5">
+                  {role === 'admin' && (
+                    <NavLink
+                      to="/admin"
+                      onClick={() => setAlertsOpen(false)}
+                      className="rounded-md px-2 py-1.5 text-[12px] text-blue-300 transition-colors hover:bg-white/[0.04]"
+                    >
+                      View in Admin → Alerts
+                    </NavLink>
+                  )}
+                  <button
+                    type="button"
+                    disabled={unacked === 0 || ackEvents.isPending}
+                    onClick={() => {
+                      ackEvents.mutate(7, {
+                        onSuccess: () => setAlertsOpen(false),
+                      });
+                    }}
+                    className="rounded-md px-2 py-1.5 text-left text-[12px] text-gray-300 transition-colors hover:bg-white/[0.04] disabled:opacity-40"
+                  >
+                    {ackEvents.isPending ? 'Dismissing…' : 'Dismiss open alerts'}
+                  </button>
+                </div>
+              </div>
+            </>
+          )}
+        </div>
+
         <span
           className={`inline-block h-2 w-2 rounded-full ${
             isBackendUp ? 'bg-emerald-400 shadow-lg shadow-emerald-400/50' : 'bg-red-400 shadow-lg shadow-red-400/50'