feat(web): add logout button to setup API keys page

Users can now switch accounts during setup

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: toto-castaldi

apps/web/src/pages/setup/SetupApiKeysPage.tsx

@@ -3,6 +3,7 @@ import { useNavigate } from 'react-router-dom';
 import {
   saveApiKey,
   testApiKey as testApiKeyFn,
+  signOut,
   API_KEY_PREFIXES,
   APP_NAME,
   type LLMProvider,
@@ -129,6 +130,11 @@ export function SetupApiKeysPage() {
     setTestStatus('idle');
   };
 
+  const handleLogout = async () => {
+    await signOut();
+    navigate('/login');
+  };
+
   return (
     <div className="flex min-h-screen items-center justify-center p-4">
       <Card className="w-full max-w-lg">
@@ -227,6 +233,18 @@ export function SetupApiKeysPage() {
                 {isLoading ? 'Salvando...' : 'Continua'}
               </Button>
             </div>
+
+            <div className="pt-4 border-t text-center">
+              <Button
+                type="button"
+                variant="ghost"
+                size="sm"
+                onClick={handleLogout}
+                className="text-muted-foreground"
+              >
+                Usa un altro account? Logout
+              </Button>
+            </div>
           </form>
         </CardContent>
       </Card>