feat(ui/alerts): InboxPage with ack + bulk-read actions

AlertRow is reused by AllAlertsPage and HistoryPage. Marking a row as read
happens when its link is followed (the detail sub-route will be added in
phase 10 polish). FIRING rows get an amber left border.

ui/src/pages/Alerts/AlertRow.tsx

@@ -0,0 +1,48 @@
+import { Link } from 'react-router';
+import { Button, useToast } from '@cameleer/design-system';
+import { AlertStateChip } from '../../components/AlertStateChip';
+import { SeverityBadge } from '../../components/SeverityBadge';
+import type { AlertDto } from '../../api/queries/alerts';
+import { useAckAlert, useMarkAlertRead } from '../../api/queries/alerts';
+import css from './alerts-page.module.css';
+
+export function AlertRow({ alert, unread }: { alert: AlertDto; unread: boolean }) {
+  const ack = useAckAlert();
+  const markRead = useMarkAlertRead();
+  const { toast } = useToast();
+
+  const onAck = async () => {
+    try {
+      await ack.mutateAsync(alert.id);
+      toast({ title: 'Acknowledged', description: alert.title, variant: 'success' });
+    } catch (e) {
+      toast({ title: 'Ack failed', description: String(e), variant: 'error' });
+    }
+  };
+
+  return (
+    <div
+      className={`${css.row} ${unread ? css.rowUnread : ''}`}
+      data-testid={`alert-row-${alert.id}`}
+    >
+      <SeverityBadge severity={alert.severity} />
+      <div className={css.body}>
+        <Link to={`/alerts/inbox/${alert.id}`} onClick={() => markRead.mutate(alert.id)}>
+          <strong>{alert.title}</strong>
+        </Link>
+        <div className={css.meta}>
+          <AlertStateChip state={alert.state} silenced={alert.silenced} />
+          <span className={css.time}>{alert.firedAt}</span>
+        </div>
+        <p className={css.message}>{alert.message}</p>
+      </div>
+      <div className={css.actions}>
+        {alert.state === 'FIRING' && (
+          <Button size="sm" variant="secondary" onClick={onAck} disabled={ack.isPending}>
+            Ack
+          </Button>
+        )}
+      </div>
+    </div>
+  );
+}

ui/src/pages/Alerts/InboxPage.tsx

@@ -1,3 +1,48 @@
+import { useMemo } from 'react';
+import { Button, SectionHeader, useToast } from '@cameleer/design-system';
+import { PageLoader } from '../../components/PageLoader';
+import { useAlerts, useBulkReadAlerts } from '../../api/queries/alerts';
+import { AlertRow } from './AlertRow';
+import css from './alerts-page.module.css';
+
 export default function InboxPage() {
-  return <div>InboxPage — coming soon</div>;
+  const { data, isLoading, error } = useAlerts({ state: ['FIRING', 'ACKNOWLEDGED'], limit: 100 });
+  const bulkRead = useBulkReadAlerts();
+  const { toast } = useToast();
+
+  const unreadIds = useMemo(
+    () => (data ?? []).filter((a) => a.state === 'FIRING').map((a) => a.id),
+    [data],
+  );
+
+  if (isLoading) return <PageLoader />;
+  if (error) return <div className={css.page}>Failed to load alerts: {String(error)}</div>;
+
+  const rows = data ?? [];
+
+  const onMarkAllRead = async () => {
+    if (unreadIds.length === 0) return;
+    try {
+      await bulkRead.mutateAsync(unreadIds);
+      toast({ title: `Marked ${unreadIds.length} as read`, variant: 'success' });
+    } catch (e) {
+      toast({ title: 'Bulk read failed', description: String(e), variant: 'error' });
+    }
+  };
+
+  return (
+    <div className={css.page}>
+      <div className={css.toolbar}>
+        <SectionHeader>Inbox</SectionHeader>
+        <Button variant="secondary" onClick={onMarkAllRead} disabled={bulkRead.isPending || unreadIds.length === 0}>
+          Mark all read
+        </Button>
+      </div>
+      {rows.length === 0 ? (
+        <div className={css.empty}>No open alerts for you in this environment.</div>
+      ) : (
+        rows.map((a) => <AlertRow key={a.id} alert={a} unread={a.state === 'FIRING'} />)
+      )}
+    </div>
+  );
 }

ui/src/pages/Alerts/alerts-page.module.css

@@ -0,0 +1,18 @@
+.page { padding: 16px; display: flex; flex-direction: column; gap: 12px; }
+.toolbar { display: flex; justify-content: space-between; align-items: center; gap: 12px; }
+.row {
+  display: grid;
+  grid-template-columns: 72px 1fr auto;
+  gap: 12px;
+  padding: 12px;
+  border: 1px solid var(--border);
+  border-radius: 8px;
+  background: var(--bg);
+}
+.rowUnread { border-left: 3px solid var(--accent); }
+.body { display: flex; flex-direction: column; gap: 4px; min-width: 0; }
+.meta { display: flex; gap: 8px; font-size: 12px; color: var(--muted); }
+.time { font-variant-numeric: tabular-nums; }
+.message { margin: 0; font-size: 13px; color: var(--fg); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.actions { display: flex; align-items: center; }
+.empty { padding: 48px; text-align: center; color: var(--muted); }