Fix citation button on Explore page (#170)

* Added key to markdown

* lint

* Updated key to remount the title

* lint

* Fixed url to be reactive

packages/viewer/src/components/Shared/Cite.svelte

@@ -1,14 +1,9 @@
 <script lang="ts">
-  import { onMount } from 'svelte'
+  import { page } from '$app/stores'
   import CopyButton from './CopyButton.svelte'
-  let url = ''
-  let markdown = ''
   export let title: string =
     'π-Base, a community database of topological counterexamples.'
-  onMount(() => {
-    url = window.location.href
-    markdown = `[${title}](${url})`
-  })
+  $: markdown = `[${title}](${$page.url})`
 </script>
 
 <div class="text-center p-2">
@@ -17,7 +12,7 @@
     <span class="text-muted">
       The pi-Base Community.
       <cite>{title}.</cite>
-      Available at: {url}
+      Available at: {$page.url}
       (Accessed: {new Date().toISOString().split('T')[0]}).
     </span>
   </small>