Improve design and add logo

frontend/src/pages/LoginPage.jsx

@@ -27,6 +27,7 @@ export function LoginPage() {
   return (
     <div className="login-wrap">
       <form className="card login-card" onSubmit={submit}>
+        <img src="/nexapg-logo.svg" alt="NexaPG" className="login-logo" />
         <div className="login-eyebrow">NexaPG Monitor</div>
         <h2>Welcome back</h2>
         <p className="login-subtitle">Sign in to access monitoring and query insights.</p>