feat: add class-variance-authority for card styling and enhance color palettes

- Introduced `class-variance-authority` to manage card component styles, allowing for flexible variant and layout options.
- Added a new color palette for "Fire" to the CSS for improved theming.
- Updated `Card` and `PostCard` components to utilize the new styling system, enhancing visual consistency and responsiveness.
- Refined layout and styling in various components for better user experience.

src/lib/components/PostCard.svelte

@@ -3,6 +3,7 @@
   import PostMeta from "./PostMeta.svelte";
   import EventBadges from "./EventBadges.svelte";
   import RustyImage from "./RustyImage.svelte";
+  import Card from "./Card.svelte";
 
   type PostWithImage = PostEntry & {
     _resolvedImageUrl?: string;
@@ -45,9 +46,10 @@
   );
 </script>
 
-<a
-  href={href}
-  class="transition-all flex flex-col text-slate-950 no-underline overflow-hidden border border-gray-200 bg-white relative {isPastEvent ? 'opacity-70 grayscale' : ''}"
+<Card
+  {href}
+  layout="post"
+  class={isPastEvent ? "opacity-70 grayscale" : ""}
 >
   <div class="relative aspect-3/2 w-full overflow-hidden bg-gray-100">
     {#if rawImg}
@@ -110,4 +112,4 @@
       {/if}
     </div>
   </div>
-</a>
+</Card>