feat(web): pending-message orchestrator (TTL discard, deferred send, online retry)

packages/web/src/hooks/useNetworkStatus.ts

@@ -0,0 +1,16 @@
+import { useEffect, useState } from 'react';
+
+export function useNetworkStatus(): boolean {
+  const [online, setOnline] = useState<boolean>(navigator.onLine);
+  useEffect(() => {
+    const on = () => setOnline(true);
+    const off = () => setOnline(false);
+    window.addEventListener('online', on);
+    window.addEventListener('offline', off);
+    return () => {
+      window.removeEventListener('online', on);
+      window.removeEventListener('offline', off);
+    };
+  }, []);
+  return online;
+}