feat: NCS-63 User account implementation (#2)

User Profile info, no game before login/register, menu bar

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Co-authored-by: Lala, Shahd <Shahd.Lala@sybit.de>
Co-authored-by: shahdlala66 <shahd.lala66@gmail.com>
Reviewed-on: #2

src/app/components/toolbar/toolbar.component.html

@@ -0,0 +1,35 @@
+<nav class="navbar">
+  <div class="container-fluid">
+    <span class="navbar-brand">NowChess</span>
+    <div class="ms-auto">
+      <div class="d-flex align-items-center gap-2">
+        <button type="button" class="app-btn" (click)="toggleTheme()">
+          {{ isDarkMode ? 'Light mode' : 'Dark mode' }}
+        </button>
+        @if (currentUser; as user) {
+        <div class="d-flex align-items-center gap-2 user-section">
+          <button type="button" class="me-btn" (click)="goToProfile()">
+            👤 {{ user.username }}
+          </button>
+          <button type="button" class="app-btn" (click)="logout()">Logout</button>
+        </div>
+        } @else {
+        <button type="button" class="app-btn" (click)="openLoginDialog()">
+          Login
+        </button>
+        <button type="button" class="app-btn" (click)="openRegisterDialog()">
+          Register
+        </button>
+        }
+      </div>
+    </div>
+  </div>
+</nav>
+
+@if (showLoginDialog) {
+<app-login-dialog (onClose)="closeLoginDialog()" (onSuccess)="onLoginSuccess()" />
+}
+
+@if (showRegisterDialog) {
+<app-register-dialog (onClose)="closeRegisterDialog()" (onSuccess)="onRegisterSuccess()" />
+}