Task #391: Live clock in Executive Meetings header

Added a `HeaderClock` component to artifacts/tx-os/src/pages/executive-meetings.tsx
that renders next to the "Export PDF" button in the sticky page header.

- Updates every 1s via setInterval (cleared on unmount)
- Locale-aware formatting via Intl.DateTimeFormat (ar / en) with hour12
- Hidden on <sm screens (`hidden sm:flex`) and on print
- Uses existing palette (text-[#0B1E3F]) + Clock lucide icon
- tabular-nums to prevent jitter as digits change
- data-testid="em-header-clock" for future tests

No deviations from plan. tx-os typecheck passes.

artifacts/tx-os/src/pages/executive-meetings.tsx

@@ -43,6 +43,7 @@ import {
   ChevronLeft,
   ChevronRight,
   Search,
+  Clock,
 } from "lucide-react";
 import { Collapsible, CollapsibleTrigger, CollapsibleContent } from "@/components/ui/collapsible";
 import { Button } from "@/components/ui/button";
@@ -758,6 +759,33 @@ export default function ExecutiveMeetingsPage() {
   );
 }
 
+function HeaderClock({ lang }: { lang: "ar" | "en" }) {
+  const [now, setNow] = useState<Date>(() => new Date());
+  useEffect(() => {
+    const id = window.setInterval(() => setNow(new Date()), 1000);
+    return () => window.clearInterval(id);
+  }, []);
+  const formatter = useMemo(
+    () =>
+      new Intl.DateTimeFormat(lang === "ar" ? "ar" : "en", {
+        hour: "numeric",
+        minute: "2-digit",
+        hour12: true,
+      }),
+    [lang],
+  );
+  return (
+    <div
+      className="hidden sm:flex items-center gap-1.5 text-sm font-medium text-[#0B1E3F] tabular-nums print:hidden"
+      data-testid="em-header-clock"
+      aria-live="off"
+    >
+      <Clock className="w-4 h-4 opacity-70" />
+      <span>{formatter.format(now)}</span>
+    </div>
+  );
+}
+
 function ExecutiveMeetingsPageInner() {
   const { t, i18n } = useTranslation();
   const [, setLocation] = useLocation();
@@ -885,6 +913,7 @@ function ExecutiveMeetingsPageInner() {
           <div className="flex-1" />
 
           <div className="flex items-center gap-2">
+            <HeaderClock lang={lang} />
             <Button
               variant="outline"
               size="sm"