Fix: Attach event listeners on login page

Event listeners were only attached after rendering main page,
not login page. Now attachEventListeners() is always called.

client/main.js

@@ -225,8 +225,8 @@ function renderApp() {
     app.innerHTML = renderLoginPage();
   } else {
     app.innerHTML = renderMainPage();
-    attachEventListeners();
   }
+  attachEventListeners();
 }
 
 function renderLoginPage() {
@@ -427,9 +427,11 @@ function renderMessage(msg) {
 // ==================== Event Handlers ====================
 
 function attachEventListeners() {
-  // Login form
+  // Login form (if on login page)
   document.getElementById('login-form')?.addEventListener('submit', handleLogin);
   
+  // Logout
+  
   // Logout
   document.getElementById('logout-btn')?.addEventListener('click', handleLogout);