add embedded checkout

frontend/src/routes/[fam]/[username]/settings/+page.svelte

@@ -324,6 +324,18 @@
 		</div>
 	{/if}
 
+	<Card title="Billing & Subscription" cols={1}>
+		<p class="hint">
+			{data.fam?.active === false
+				? 'Your subscription is paused — interactions and payments are disabled.'
+				: 'Manage your plan, billing details, or pause your subscription.'}
+		</p>
+		<div class="actions">
+			<Button href="/account" variant="primary" size="sm">Account & Billing</Button>
+			<Button href="/subscriptions" variant="secondary" size="sm">Plans</Button>
+		</div>
+	</Card>
+
 	<Card title="Data" cols={1}>
 		<div class="actions">
 			<Button variant="ghost" size="sm" disabled>Download CSV (coming soon)</Button>