feat(frontend): add apiFetch wrapper for automatic auth token injection

Centralizes auth token management into a reusable apiFetch() helper and getAuthHeaders() utility, eliminating inline Bearer token logic across all frontend files.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

frontend/src/lib/components/admin/BusinessSettings.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
 	import { authStore } from '$lib/stores/auth.svelte';
+	import { apiFetch } from '$lib/utils/api';
 	import { toast } from 'svelte-sonner';
 	import { Button } from '$lib/components/ui/button';
 	import * as Card from '$lib/components/ui/card';
@@ -36,9 +37,7 @@
 	async function fetchSettings() {
 		loading = true;
 		try {
-			const res = await fetch('/api/admin/settings', {
-				headers: { Authorization: `Bearer ${authStore.currentToken}` }
-			});
+			const res = await apiFetch('/api/admin/settings');
 			if (res.ok) {
 				settings = await res.json();
 			} else {
@@ -237,11 +236,10 @@
 				return;
 			}
 
-			const res = await fetch('/api/admin/settings', {
+			const res = await apiFetch('/api/admin/settings', {
 				method: 'PUT',
 				headers: {
-					'Content-Type': 'application/json',
-					Authorization: `Bearer ${authStore.currentToken}`
+					'Content-Type': 'application/json'
 				},
 				body: JSON.stringify(patch)
 			});