feat(ui): add wedding theme styles and layout components

* Introduced wedding-themed CSS variables for styling.
* Created layout component for the wedding site with navigation and countdown.
* Added RSVP and photo upload pages with form handling.
* Implemented QR code page for wedding site access.
* Configured TypeScript and Vite for the project.
* Added robots.txt for search engine crawling.

ui/src/routes/+page.svelte

@@ -0,0 +1,49 @@
+<script lang="ts">
+  import PhotoBackground from "$lib/components/PhotoBackground.svelte";
+  import { createWeddingInfo, formatFullDate } from "$lib/wedding-info.svelte";
+  import { createRsvpStatus } from "$lib/rsvp-status.svelte";
+
+  const wedding = createWeddingInfo();
+  const rsvpStatus = createRsvpStatus();
+</script>
+
+<section
+  class="relative flex flex-1 items-center justify-center overflow-hidden px-4 py-16 text-center"
+>
+  <PhotoBackground />
+
+  <div
+    class="border-surface-50/70 relative z-10 flex max-w-xl flex-col items-center gap-6 border px-6 py-12 sm:px-14 sm:py-16"
+  >
+    <h1 class="text-surface-50 font-malibu text-6xl sm:text-8xl">
+      Zoé &amp; Shaldon
+    </h1>
+    <p class="text-surface-100 text-2xl">are getting married</p>
+
+    <div class="flex flex-col gap-1">
+      <p class="text-surface-50 text-2xl font-medium sm:text-3xl">
+        {formatFullDate(wedding.date)}
+      </p>
+      <p class="text-surface-200 text-2xl tracking-wide">
+        {wedding.ceremonyTime}
+      </p>
+    </div>
+
+    <div class="flex flex-col gap-0.5">
+      <p class="text-surface-50 text-2xl">{wedding.venueName}</p>
+      <p class="text-surface-100 text-2xl">{wedding.venueAddress}</p>
+    </div>
+
+    <div class="mt-6 flex flex-wrap items-center justify-center gap-4">
+      {#if !rsvpStatus.submitted}
+        <a href="/rsvp" class="btn preset-filled-secondary-500 text-2xl">RSVP</a
+        >
+      {:else}
+        <p class="text-secondary-300 text-2xl">✓ You've RSVP'd — thank you!</p>
+      {/if}
+      <a href="/photos" class="btn preset-filled-primary-500 text-2xl"
+        >Share photos</a
+      >
+    </div>
+  </div>
+</section>