fix: use client signIn helper on home and bump @zitadel/tanstack-auth to 1.1.2

The home Login button hardcoded a GET to /api/auth/signin/zitadel, which
Auth.js v5 rejects with a Configuration error. Use the SDK client signIn
helper (CSRF+POST) and bump the SDK to the version that ships the fix.

Author: mridang

app/routes/index.tsx

@@ -1,4 +1,5 @@
 import { createFileRoute } from '@tanstack/react-router';
+import { signIn } from '@zitadel/tanstack-auth/client';
 import { Header } from '~/components/Header';
 import { Footer } from '~/components/Footer';
 
@@ -112,8 +113,11 @@ function IndexPage() {
                       />
                     </div>
                   </div>
-                  <a
-                    href="/api/auth/signin/zitadel"
+                  <button
+                    type="button"
+                    onClick={() =>
+                      void signIn('zitadel', { callbackUrl: '/profile' })
+                    }
                     className="mb-6 flex w-full cursor-pointer items-center justify-center space-x-2 rounded-lg bg-blue-600 px-4 py-3 font-semibold text-white transition duration-200 hover:bg-blue-700"
                   >
                     <svg
@@ -132,7 +136,7 @@ function IndexPage() {
                       />
                     </svg>
                     <span>Login</span>
-                  </a>
+                  </button>
                   <div className="text-center">
                     <p className="mb-4 text-sm text-gray-500">
                       What happens when you click the button:

package-lock.json

@@ -24,7 +24,7 @@
     "@tanstack/react-router": "^1.168.0",
     "@tanstack/react-start": "^1.168.0",
     "@tanstack/start-storage-context": "^1.167.0",
-    "@zitadel/tanstack-auth": "^1.0.0",
+    "@zitadel/tanstack-auth": "^1.1.2",
     "openid-client": "^6.6.3",
     "react": "^19",
     "react-dom": "^19"