fix: remove auto-redirect from API client on 401

The API client was redirecting to /login on any 401 response,
including the checkAuth() call in the layout. This caused a
redirect loop that cleared the token. Auth redirects are now
handled solely by the layout's checkAuth() flow.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/routes/+layout.svelte

@@ -13,6 +13,8 @@
 			const path = window.location.pathname;
 			const publicPaths = ['/login', '/setup'];
 
+			console.log('[auth]', { path, needsSetup: getNeedsSetup(), authenticated: isAuthenticated(), token: !!localStorage.getItem('nb_token') });
+
 			if (getNeedsSetup() && path !== '/setup') {
 				window.location.href = '/setup';
 			} else if (!getNeedsSetup() && !isAuthenticated() && !publicPaths.includes(path)) {