refactor: move document domain core to lib/document/

Moves ~25 components, utils (search, filename, groupDocuments,
documentStatusLabel, validateFile), bulkSelection store, and
TranscriptionSection sub-component. Fixes broken relative imports.

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

frontend/src/lib/document/DocumentViewer.svelte

@@ -0,0 +1,115 @@
+<script lang="ts">
+import { m } from '$lib/paraglide/messages.js';
+import PdfViewer from '$lib/components/PdfViewer.svelte';
+
+type Doc = {
+	id: string;
+	filePath?: string | null;
+	contentType?: string | null;
+	fileHash?: string | null;
+};
+
+type DrawRect = { x: number; y: number; width: number; height: number; pageNumber: number };
+
+type Props = {
+	doc: Doc;
+	fileUrl: string;
+	isLoading: boolean;
+	error: string;
+	transcribeMode?: boolean;
+	blockNumbers?: Record<string, number>;
+	annotationReloadKey?: number;
+	activeAnnotationId: string | null;
+	annotationsDimmed?: boolean;
+	flashAnnotationId?: string | null;
+	onAnnotationClick: (id: string) => void;
+	onTranscriptionDraw?: (rect: DrawRect) => void;
+	onDeleteAnnotationRequest?: (annotationId: string) => void;
+};
+
+let {
+	doc,
+	fileUrl,
+	isLoading,
+	error,
+	transcribeMode = false,
+	blockNumbers = {},
+	annotationReloadKey = 0,
+	activeAnnotationId = $bindable(),
+	annotationsDimmed = false,
+	flashAnnotationId = null,
+	onAnnotationClick,
+	onTranscriptionDraw,
+	onDeleteAnnotationRequest
+}: Props = $props();
+</script>
+
+<div class="absolute inset-0 bg-pdf-bg">
+	{#if isLoading}
+		<div class="flex h-full flex-col items-center justify-center text-accent">
+			<svg
+				class="mb-4 h-8 w-8 animate-spin"
+				xmlns="http://www.w3.org/2000/svg"
+				fill="none"
+				viewBox="0 0 24 24"
+			>
+				<circle class="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" stroke-width="4"
+				></circle>
+				<path
+					class="opacity-75"
+					fill="currentColor"
+					d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z"
+				></path>
+			</svg>
+			<span class="font-sans text-sm tracking-wide">{m.doc_loading()}</span>
+		</div>
+	{:else if error}
+		<div class="flex h-full flex-col items-center justify-center px-4 text-center text-ink-3">
+			<p class="mb-2 font-serif">{error}</p>
+			{#if doc.filePath}
+				<a
+					href="/api/documents/{doc.id}/file"
+					target="_blank"
+					class="text-sm underline hover:text-white"
+				>
+					{m.doc_download_link()}
+				</a>
+			{/if}
+		</div>
+	{:else if !doc.filePath}
+		<div class="flex h-full flex-col items-center justify-center text-ink-3">
+			<div class="mb-6 rounded-full bg-surface/5 p-8">
+				<img
+					src="/degruyter-icons/Simple/Medium-24px/SVG/Action/PDF-Document-MD.svg"
+					alt=""
+					aria-hidden="true"
+					class="h-12 w-12 opacity-50 invert"
+				/>
+			</div>
+			<p class="font-sans text-sm tracking-wide uppercase">{m.doc_no_scan()}</p>
+		</div>
+	{:else if fileUrl && doc.contentType?.startsWith('application/pdf')}
+		<PdfViewer
+			url={fileUrl}
+			documentId={doc.id}
+			transcribeMode={transcribeMode}
+			blockNumbers={blockNumbers}
+			annotationReloadKey={annotationReloadKey}
+			bind:activeAnnotationId={activeAnnotationId}
+			annotationsDimmed={annotationsDimmed}
+			flashAnnotationId={flashAnnotationId}
+			onAnnotationClick={onAnnotationClick}
+			onTranscriptionDraw={onTranscriptionDraw}
+			onDeleteAnnotationRequest={onDeleteAnnotationRequest}
+			documentFileHash={doc.fileHash ?? null}
+		/>
+	{:else if fileUrl}
+		<div class="flex h-full w-full items-center justify-center overflow-auto p-8">
+			<img
+				src={fileUrl}
+				alt={m.doc_image_alt()}
+				class="max-h-full max-w-full object-contain shadow-2xl"
+			/>
+		</div>
+	{/if}
+</div>