refactor: migrate to Svelte 5

use runes ($props, $state, $derived, $effect, etc)

apps/website/src/components/molecules/PostCard/PostCard.svelte

@@ -6,19 +6,30 @@
     import { cx } from 'classix'
     import Image from '$components/atoms/Image.svelte'
 
-    export let street: string
-    export let location: string
-    export let region: string = undefined
-    export let country: string
-    export let flagId: string
-    export let size: string = undefined
+    let {
+        street,
+        location,
+        region,
+        country,
+        flagId,
+        size,
+        ...props
+    }: {
+        street: string
+        location: string
+        region?: string
+        country: string
+        flagId: string
+        size?: string
+        class?: string
+    } = $props()
 
-    const className = 'postcard'
-    $: classes = cx(
-        className,
-        ...[size].map(variant => variant && `${className}--${variant}`),
-        $$props.class
-    )
+    const cardClass = 'postcard'
+    const classes = $derived(cx(
+        cardClass,
+        ...[size].map(variant => variant && `${cardClass}--${variant}`),
+        props.class,
+    ))
 </script>
 
 <div class={classes}>