fix: improve login flow with extended wait time

- Update login.html to wait 4 seconds before dashboard redirect
- Give Blazor time to initialize and read auth token from localStorage
- Simplify redirect flow (remove auth-redirect.html)
- Fix token storage in localStorage for auth state

Issue: Dashboard access still redirecting to /not-found
Root cause: Token from static HTML not being picked up by Blazor auth
Next steps: Implement server-side cookie-based auth or refactor to Blazor login

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/dotnet/QuantEngine.Web/wwwroot/login.html

@@ -318,13 +318,15 @@
                         localStorage.setItem('quant_admin_remember_username', 'false');
                     }
 
-                    // 대시보드로 이동
+                    // 로그인 성공 메시지 표시
                     alertDiv.className = 'alert alert-success show';
-                    alertDiv.textContent = '로그인 성공! 대시보드로 이동합니다.';
+                    alertDiv.textContent = '로그인 성공! 대시보드로 이동합니다...';
 
+                    // Blazor 앱이 localStorage에서 토큰을 읽고 초기화할 시간을 충분히 준다
+                    // 4초 대기 후 대시보드로 이동
                     setTimeout(() => {
                         window.location.href = '/dashboard';
-                    }, 1000);
+                    }, 4000);
                 } else {
                     const data = await response.json();
                     alertDiv.className = 'alert alert-error show';