feat: add health check route

app/routes/healthz.tsx

@@ -0,0 +1,29 @@
+import { loadContext } from '~/utils/config/headplane'
+import { HeadscaleError, pull } from '~/utils/headscale'
+import log from '~/utils/log'
+
+export async function loader() {
+	const context = await loadContext()
+
+	try {
+		// Doesn't matter, we just need a 401
+		await pull('v1/', 'wrongkey')
+	} catch (e) {
+		if (!(e instanceof HeadscaleError)) {
+			log.debug('Healthz', 'Headscale is not reachable')
+			return new Response('Headscale is not reachable', {
+				status: 500,
+				headers: {
+					'Content-Type': 'text/plain',
+				},
+			})
+		}
+	}
+
+	return new Response('OK', {
+		status: 200,
+		headers: {
+			'Content-Type': 'text/plain',
+		},
+	})
+}