Categorize components/ui into primitives, overlay, media, forms and layout

Splits the flat 38-component ui/ folder into primitives/ (generic
controls), overlay/ (menus/modals), media/ (music-domain display
components), forms/ (composite entity forms) and layout/ (page
scaffolding), and updates every import path accordingly.

web-player/src/lib/components/ui/media/ExplicitBadge.svelte

@@ -0,0 +1,13 @@
+<script lang="ts">
+	interface Props {
+		class?: string;
+	}
+
+	let { class: klass = '' }: Props = $props();
+</script>
+
+<span
+	class="grid size-4 shrink-0 place-items-center rounded-tag bg-fg-3 text-xs leading-4 font-bold text-bg {klass}"
+	title="Contenido explícito"
+	aria-label="Contenido explícito">E</span
+>