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/layout.tsx

@@ -2,6 +2,7 @@ import type { Metadata } from "next";
 import { Geist } from "next/font/google";
 import "./globals.css";
 import { Sidebar } from "@/components/sidebar";
+import { Toaster } from "sonner";
 
 const geistSans = Geist({
   variable: "--font-geist-sans",
@@ -27,6 +28,17 @@ export default function RootLayout({
             {children}
           </main>
         </div>
+        <Toaster 
+          theme="dark" 
+          position="top-right"
+          toastOptions={{
+            style: {
+              background: '#171717',
+              border: '1px solid #262626',
+              color: '#fff',
+            },
+          }}
+        />
       </body>
     </html>
   );

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) {

admin-web/app/trainers/page.tsx

@@ -6,6 +6,7 @@ import { Button } from "@/components/ui/button";
 import { Card, CardContent } from "@/components/ui/card";
 import { Plus, Trash2, Edit, Loader2, Users, AlertCircle } from "lucide-react";
 import Link from "next/link";
+import { toast } from "sonner";
 import type { Database } from "@/lib/supabase";
 
 type Trainer = Database["public"]["Tables"]["trainers"]["Row"];
@@ -56,9 +57,12 @@ export default function TrainersPage() {
       const { error } = await supabase.from("trainers").delete().eq("id", id);
       if (error) throw error;
       setTrainers(trainers.filter((t) => t.id !== id));
+      toast.success("Trainer deleted", {
+        description: "The trainer has been removed successfully."
+      });
     } catch (error) {
       console.error("Failed to delete trainer:", error);
-      alert("Failed to delete trainer");
+      toast.error("Failed to delete trainer");
     } finally {
       setDeletingId(null);
     }

admin-web/app/workouts/page.tsx

@@ -16,6 +16,7 @@ import {
   TableRow,
 } from "@/components/ui/table";
 import { Plus, Trash2, Edit, Loader2, Eye } from "lucide-react";
+import { toast } from "sonner";
 import type { Database } from "@/lib/supabase";
 
 type Workout = Database["public"]["Tables"]["workouts"]["Row"];
@@ -54,9 +55,12 @@ export default function WorkoutsPage() {
       const { error } = await supabase.from("workouts").delete().eq("id", id);
       if (error) throw error;
       setWorkouts(workouts.filter((w) => w.id !== id));
+      toast.success("Workout deleted", {
+        description: "The workout has been removed successfully."
+      });
     } catch (error) {
       console.error("Failed to delete workout:", error);
-      alert("Failed to delete workout");
+      toast.error("Failed to delete workout");
     } finally {
       setDeletingId(null);
     }