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

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

---------

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

src/app/components/login-dialog/login-dialog.component.html

@@ -0,0 +1,36 @@
+<div class="dialog-overlay" (click)="closeDialog()">
+  <div class="dialog-card" (click)="$event.stopPropagation()">
+    <div class="dialog-title">LOGIN</div>
+
+    <form [formGroup]="loginForm" (ngSubmit)="onSubmit()">
+      <label for="username" class="sr-only">Username</label>
+      <input id="username" type="text" class="dialog-input" formControlName="username" placeholder="Username"
+        [disabled]="isLoading" />
+      @if (loginForm.get('username')?.invalid && loginForm.get('username')?.touched) {
+      <small class="text-danger">Username must be at least 3 characters</small>
+      }
+
+      <label for="password" class="sr-only">Password</label>
+      <input id="password" type="password" class="dialog-input" formControlName="password" placeholder="Password"
+        [disabled]="isLoading" />
+      @if (loginForm.get('password')?.invalid && loginForm.get('password')?.touched) {
+      <small class="text-danger">Password must be at least 6 characters</small>
+      }
+
+      @if (errorMessage) {
+      <div class="error-banner">{{ errorMessage }}</div>
+      }
+
+      <div class="dialog-actions">
+        <button type="button" class="app-btn" (click)="openRegister()">Create account</button>
+        <button type="button" class="app-btn" (click)="closeDialog()">Cancel</button>
+        <button type="submit" class="app-btn" [disabled]="isLoading || loginForm.invalid">
+          @if (isLoading) {
+          <span class="spinner-border spinner-border-sm me-2" role="status" aria-hidden="true"></span>
+          }
+          Login
+        </button>
+      </div>
+    </form>
+  </div>
+</div>