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/primitives/Field.svelte

@@ -0,0 +1,27 @@
+<script lang="ts">
+	import type { Snippet } from 'svelte';
+
+	interface Props {
+		label?: string;
+		for?: string;
+		class?: string;
+		hint?: Snippet;
+		children: Snippet;
+	}
+
+	let { label, for: forId, class: klass = '', hint, children }: Props = $props();
+</script>
+
+<div class="flex min-w-0 flex-col {klass}">
+	{#if label}
+		<label for={forId} class="mb-2 block text-sm font-medium text-fg-2">
+			{label}
+		</label>
+	{/if}
+	{@render children()}
+	{#if hint}
+		<div class="mt-2 flex items-center justify-between gap-3 text-xs text-muted">
+			{@render hint()}
+		</div>
+	{/if}
+</div>