feat: implement beautiful toast notifications with Sonner

- Install sonner package for toast notifications
- Add Toaster component to root layout with dark theme styling
- Replace all alert() calls with toast.success() and toast.error()
- Add descriptive messages for success states
- Toast notifications match the app's dark theme design

admin-web/app/media/page.tsx

@@ -6,6 +6,7 @@ import { Button } from "@/components/ui/button";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
 import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs";
 import { Upload, Film, Image as ImageIcon, User, Loader2 } from "lucide-react";
+import { toast } from "sonner";
 
 const BUCKETS = [
   { id: "videos", label: "Videos", icon: Film, types: "video/*" },
@@ -34,10 +35,10 @@ export default function MediaPage() {
 
       if (uploadError) throw uploadError;
 
-      alert("File uploaded successfully!");
+      toast.success("File uploaded successfully!");
     } catch (error) {
       console.error("Upload failed:", error);
-      alert("Upload failed: " + (error instanceof Error ? error.message : "Unknown error"));
+      toast.error("Upload failed: " + (error instanceof Error ? error.message : "Unknown error"));
     } finally {
       setUploading(false);
       if (fileInputRef.current) {