Use global value to check for current Shop product

Also add other stores types to hint on expected values

src/routes/shop/index.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
     import { getContext } from 'svelte'
+    import { shopCurrentProductSlug } from '$utils/stores/shop'
     // Components
     import PageTransition from '$components/PageTransition.svelte'
     import Metas from '$components/Metas.svelte'
@@ -11,6 +12,9 @@
     export let shopProduct: any
 
     const { posters } = getContext('shop')
+
+    // Update current random product slug
+    $shopCurrentProductSlug = product.location.slug
 </script>
 
 <Metas