add: Update checker

fix: Jellyfin user id being hard coded

src/lib/components/UpdateChecker.svelte

@@ -0,0 +1,28 @@
+<script lang="ts">
+	import { skippedVersion } from '$lib/localstorage';
+	import axios from 'axios';
+	import IconButton from './IconButton.svelte';
+	import { Cross2 } from 'radix-icons-svelte';
+	import { log } from '$lib/utils';
+	import { version } from '$app/environment';
+
+	let visible = true;
+
+	function fetchLatestVersion() {
+		return axios
+			.get('https://api.github.com/repos/aleksilassila/reiverr/tags')
+			.then((res) => res.data?.[0]?.name)
+			.then(log);
+	}
+</script>
+
+{#await fetchLatestVersion() then latestVersion}
+	{#if latestVersion !== `v${version}` && latestVersion !== $skippedVersion && visible}
+		<div class="fixed inset-x-0 bottom-0 p-2 flex items-center justify-center z-20 bg-stone-800">
+			<a href="https://github.com/aleksilassila/reiverr">New version is available!</a>
+			<IconButton on:click={() => (visible = false)} class="absolute right-8 inset-y-0">
+				<Cross2 size={20} />
+			</IconButton>
+		</div>
+	{/if}
+{/await}