feat: add success toasts for create operations and login

- Add toast.success when workout is created or updated
- Add toast.success when user logs in successfully
- Show descriptive messages with entity names
- Improves user feedback for successful operations

admin-web/app/login/page.tsx

@@ -2,6 +2,7 @@
 
 import { useState } from "react";
 import { useRouter } from "next/navigation";
+import { toast } from "sonner";
 import { supabase } from "@/lib/supabase";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
@@ -43,6 +44,10 @@ export default function LoginPage() {
         throw new Error("Not authorized as admin");
       }
 
+      toast.success("Welcome back!", {
+        description: "You have successfully signed in."
+      })
+      
       // Force a full page reload to ensure middleware picks up the session
       window.location.href = "/";
     } catch (err) {