Implement lamp brightness debouncing

frontend/src/lib/components/Lamp.svelte

@@ -2,9 +2,13 @@
 	export let brightnessChange = (brightness: number) => {};
 	export let brightness: number;
 
-	function handleBrightnessChange(event) {
-		brightness = event.target.value;
+	let timer: number;
+	function handleBrightnessChange(event: Event) {
+		clearTimeout(timer);
+		timer = setTimeout(() => {
+			brightness = event.target?.value || 0;
 			brightnessChange(brightness);
+		}, 300);
 	}
 </script>