rename /setup route to /settings, fix hooks violation crash on settings page

useState was called after conditional return (React hooks rules violation),
causing the settings page to crash. moved all hooks to top level.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/routes/__root.tsx

@@ -54,7 +54,7 @@ function RootLayout() {
 				<NavLink to="/execute">Execute</NavLink>
 				<div className="flex-1" />
 				<NavLink to="/nodes">Nodes</NavLink>
-				<NavLink to="/setup">Settings</NavLink>
+				<NavLink to="/settings">Settings</NavLink>
 			</nav>
 			<main className="max-w-[1600px] mx-auto px-5 pt-4 pb-12">
 				<Outlet />