refactor: externalize all SVG icons to partials/icons

partials/scroll-top.hbs

@@ -10,7 +10,5 @@
     class="fixed bottom-8 right-8 z-40 p-3 rounded-lg shadow-xl bg-[var(--brand-primary)] text-[var(--bg-primary)] hover:bg-[var(--brand-secondary)] hover:scale-110 active:scale-95 transition-all duration-300 group"
     aria-label="Scroll to top"
     x-cloak>
-    <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2.5" stroke="currentColor" class="w-6 h-6 transform group-hover:-translate-y-1 transition-transform duration-300">
-        <path stroke-linecap="round" stroke-linejoin="round" d="M4.5 10.5 12 3m0 0 7.5 7.5M12 3v18" />
-    </svg>
+    {{> "icons/arrow-up" class="w-6 h-6 transform group-hover:-translate-y-1 transition-transform duration-300"}}
 </button>