Sauna: Add update timestamp to sauna api

webui/src/routes/sauna/+page.svelte

@@ -2,10 +2,12 @@
 	import { onMount } from "../../../node_modules/svelte/internal";
 	import icon from "$lib/images/sauna.svg"
 
-	let backend_url = "https://home.blackfinn.de/sauna/sample";
+	let backend_url = "https://home.blackfinn.de/api/sauna";
 
 	let temperature_value = 0.0
 	let temperature_unit = "°C"
+	let time = "00:00:00";
+	let updated = false;
 
 	function get_temperature() {
 		fetch(backend_url)
@@ -13,6 +15,8 @@
 		.then(data => {
 			temperature_unit = data.unit
 			temperature_value = data.value
+			time = data.time.slice(11, 19)
+			updated = JSON.parse(data.valid);
 		}).catch(error => {
 			console.log(error);
 			return [];
@@ -38,5 +42,8 @@
 	<figure>
 		<img src={icon} alt="Sauna" width=150/>
 	</figure>
-	<h1>{temperature_value} {temperature_unit}</h1>
+	{#if updated}
+		<div>{time} Uhr:</div>
+		<h1>{temperature_value} {temperature_unit}</h1>
+	{/if}
 </section>