refactor(web): migrate from Vike+React to SvelteKit

- Replace Vike+React with SvelteKit for simpler SSR and routing
- Update WASM build output paths from public/ to static/
- Add wasm-opt integration for WASM size optimization
- Streamline tooling: remove ESLint, Prettier configs (use defaults)
- Move build.rs to pacman-server/ (frontend no longer needs it)

web/src/routes/+error.svelte

@@ -0,0 +1,12 @@
+<script lang="ts">
+	import { page } from '$app/stores';
+</script>
+
+<div class="flex flex-col items-center justify-center min-h-[50vh] text-center px-4">
+	<h1 class="text-4xl font-bold mb-4">
+		{$page.status === 404 ? 'Page Not Found' : 'Internal Error'}
+	</h1>
+	<p class="text-gray-400">
+		{$page.status === 404 ? 'This page could not be found.' : 'Something went wrong.'}
+	</p>
+</div>