feat(enrich): add metadata enrichment queue UI

Home page shows "Needs metadata" card when incomplete documents exist.
/enrich list shows all incomplete documents; /enrich/[id] provides a
split PDF-preview + compact form view with Skip / Save / Save & reviewed
actions that auto-advance through the queue.

New document page gets Save vs Save & reviewed split. Edit page gets
"Mark for review" secondary button to push a document back into the queue.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/enrich/+page.svelte

@@ -0,0 +1,106 @@
+<script lang="ts">
+import { m } from '$lib/paraglide/messages.js';
+
+let { data } = $props();
+
+const documents = $derived(data.documents);
+const count = $derived(documents.length);
+
+function formatUploadDate(createdAt: string): string {
+	return new Intl.DateTimeFormat('de-DE', {
+		day: 'numeric',
+		month: 'long',
+		year: 'numeric'
+	}).format(new Date(createdAt));
+}
+</script>
+
+<div class="mx-auto max-w-4xl px-4 py-10">
+	<!-- Back Link -->
+	<a
+		href="/"
+		class="group mb-4 inline-flex items-center font-sans text-xs font-bold tracking-widest text-gray-500 uppercase transition-colors hover:text-brand-navy"
+	>
+		<img
+			src="/degruyter-icons/Simple/Medium-24px/SVG/Action/Arrow/Arrow-Left-MD.svg"
+			alt=""
+			aria-hidden="true"
+			class="mr-2 h-4 w-4 transform transition-transform group-hover:-translate-x-1"
+		/>
+		{m.enrich_list_back()}
+	</a>
+
+	<!-- Page Header -->
+	<div class="border-brand-sand mb-8 flex items-center justify-between border-b pb-6">
+		<div>
+			<h1 class="font-serif text-3xl font-medium text-brand-navy">
+				{m.enrich_list_heading()}
+			</h1>
+			{#if count > 0}
+				<p class="mt-2 font-sans text-sm text-brand-navy/60">
+					{count}
+					{m.enrich_list_count()}
+				</p>
+			{/if}
+		</div>
+
+		{#if count > 0}
+			<a
+				href="/enrich/{documents[0].id}"
+				class="bg-brand-navy px-5 py-2 font-sans text-xs font-bold tracking-widest text-white uppercase transition-colors hover:bg-brand-navy/90"
+			>
+				{m.enrich_list_start()}
+			</a>
+		{/if}
+	</div>
+
+	<!-- Empty State -->
+	{#if count === 0}
+		<div
+			class="border-brand-sand flex flex-col items-center justify-center rounded-sm border border-dashed bg-white py-20 text-center"
+		>
+			<div class="bg-brand-sand/60 mb-4 flex h-14 w-14 items-center justify-center rounded-full">
+				<img
+					src="/degruyter-icons/Simple/Medium-24px/SVG/Action/Check/Check-Circle-MD.svg"
+					alt=""
+					aria-hidden="true"
+					class="h-7 w-7 opacity-50"
+				/>
+			</div>
+			<p class="font-serif text-lg font-medium text-brand-navy">
+				{m.enrich_list_empty_heading()}
+			</p>
+			<p class="mt-2 max-w-xs font-sans text-sm text-brand-navy/60">
+				{m.enrich_list_empty_body()}
+			</p>
+		</div>
+	{:else}
+		<!-- Document Rows -->
+		<div class="border-brand-sand border bg-white shadow-sm">
+			<ul class="divide-brand-sand divide-y">
+				{#each documents as doc (doc.id)}
+					<li class="group hover:bg-brand-sand/30 transition-colors duration-200">
+						<a href="/enrich/{doc.id}" class="flex items-center justify-between p-6">
+							<div class="min-w-0 flex-1">
+								<p
+									class="font-serif text-lg font-medium text-brand-navy decoration-brand-mint decoration-2 underline-offset-4 group-hover:underline"
+								>
+									{doc.title || doc.originalFilename}
+								</p>
+								<p class="mt-1 font-sans text-xs text-brand-navy/50">
+									{formatUploadDate(doc.createdAt)}
+								</p>
+							</div>
+							<img
+								src="/degruyter-icons/Simple/Medium-24px/SVG/Action/Arrow/Arrow-Right-MD.svg"
+								alt=""
+								aria-hidden="true"
+								class="ml-4 h-5 w-5 shrink-0 opacity-30 transition-opacity group-hover:opacity-70"
+							/>
+						</a>
+					</li>
+				{/each}
+			</ul>
+		</div>
+	{/if}
+</div>