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/overlay/GlassMenu.svelte

@@ -0,0 +1,15 @@
+<script lang="ts">
+	import type { Snippet } from 'svelte';
+
+	interface Props {
+		class?: string;
+		style?: string;
+		children: Snippet;
+	}
+
+	let { class: klass = '', style = '', children }: Props = $props();
+</script>
+
+<div class="glass-panel animate-pop rounded-panel border border-hairline p-1.5 {klass}" {style}>
+	{@render children()}
+</div>