feat: add PWA support with manifest configuration and offline connectivity indicator

components/ui/offline-indicator.tsx

@@ -0,0 +1,33 @@
+"use client";
+
+import { useEffect, useState } from "react";
+import { WifiOff } from "lucide-react";
+
+export function OfflineIndicator() {
+  const [isOnline, setIsOnline] = useState(true);
+
+  useEffect(() => {
+    // Sadece client-side'da çalışır
+    setIsOnline(navigator.onLine);
+
+    const handleOnline = () => setIsOnline(true);
+    const handleOffline = () => setIsOnline(false);
+
+    window.addEventListener("online", handleOnline);
+    window.addEventListener("offline", handleOffline);
+
+    return () => {
+      window.removeEventListener("online", handleOnline);
+      window.removeEventListener("offline", handleOffline);
+    };
+  }, []);
+
+  if (isOnline) return null;
+
+  return (
+    <div className="fixed bottom-4 right-4 z-50 flex items-center gap-2 rounded-lg bg-destructive px-4 py-2 text-sm font-medium text-destructive-foreground shadow-lg animate-in fade-in slide-in-from-bottom-4">
+      <WifiOff className="h-4 w-4" />
+      Çevrimdışı moddasınız. Değişiklikler senkronize edilmeyecek.
+    </div>
+  );
+}