feat: add health check

frontend/src/routes/health/+server.ts

@@ -0,0 +1,20 @@
+import AppConfigService from '$lib/services/app-config-service';
+import type { RequestHandler } from '@sveltejs/kit';
+
+export const GET: RequestHandler = async () => {
+	const appConfigService = new AppConfigService();
+	let backendOk = true;
+	await appConfigService.list().catch(() => (backendOk = false));
+
+	return new Response(
+		JSON.stringify({
+			status: backendOk ? 'HEALTHY' : 'UNHEALTHY'
+		}),
+		{
+			status: backendOk ? 200 : 500,
+			headers: {
+				'content-type': 'application/json'
+			}
+		}
+	);
+};