Add ping endpoint, update-refresh prompt, and dark-mode polish

resources/js/api/client.js

@@ -129,6 +129,15 @@ export async function fetchVersion() {
     return apiFetch('/version')
 }
 
+export async function fetchPing() {
+    const response = await fetch('/ping', {
+        headers: {
+            Accept: 'application/json',
+        },
+    })
+    return parseResponse(response)
+}
+
 export async function fetchVersionCheck() {
     return apiFetch('/version/check')
 }