refactor: move document transcription, annotation, viewer sub-packages

- transcription/: TranscriptionBlock, Column, EditView, PanelHeader, ReadView,
  Section + transcriptionMarkers, blockConflictMerge, saveBlockWithConflictRetry
  + useBlockAutoSave, useBlockDragDrop hooks
- annotation/: AnnotationLayer, AnnotationShape, AnnotationEditOverlay
- viewer/: PdfViewer, PdfControls + useFileLoader, usePdfRenderer hooks

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

frontend/src/lib/document/transcription/TranscriptionColumn.svelte.spec.ts

@@ -0,0 +1,85 @@
+import { describe, it, expect, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+import TranscriptionColumn from './TranscriptionColumn.svelte';
+import type { components } from '$lib/generated/api';
+
+type TranscriptionQueueItemDTO = components['schemas']['TranscriptionQueueItemDTO'];
+
+afterEach(cleanup);
+
+function makeDoc(overrides: Partial<TranscriptionQueueItemDTO> = {}): TranscriptionQueueItemDTO {
+	return {
+		id: 'doc-1',
+		title: 'Test Dokument',
+		annotationCount: 0,
+		textedBlockCount: 0,
+		reviewedBlockCount: 0,
+		contributors: [],
+		hasMoreContributors: false,
+		...overrides
+	};
+}
+
+describe('TranscriptionColumn', () => {
+	it('renders document list when docs are provided', async () => {
+		const doc1 = makeDoc({ id: 'doc-1', title: 'Familienbrief' });
+		const doc2 = makeDoc({ id: 'doc-2', title: 'Tagebuch Eintrag' });
+
+		render(TranscriptionColumn, { props: { docs: [doc1, doc2], weeklyCount: 0 } });
+
+		await expect.element(page.getByText('Familienbrief')).toBeInTheDocument();
+		await expect.element(page.getByText('Tagebuch Eintrag')).toBeInTheDocument();
+	});
+
+	it('renders dashed empty state when docs array is empty', async () => {
+		render(TranscriptionColumn, { props: { docs: [], weeklyCount: 0 } });
+
+		await expect
+			.element(page.getByText('Keine Dokumente warten auf Transkription.'))
+			.toBeInTheDocument();
+	});
+
+	it('renders progress bar when textedBlockCount > 0', async () => {
+		const doc = makeDoc({
+			id: 'doc-1',
+			title: 'Brief mit Blöcken',
+			annotationCount: 4,
+			textedBlockCount: 2
+		});
+
+		render(TranscriptionColumn, { props: { docs: [doc], weeklyCount: 0 } });
+
+		// The progress text should show "2 / 4 Blöcke"
+		await expect.element(page.getByText('2 / 4 Blöcke')).toBeInTheDocument();
+
+		// A progress bar div should exist (the visual bar)
+		const progressBar = document.querySelector('.h-1.flex-1');
+		expect(progressBar).not.toBeNull();
+	});
+
+	it('renders dash placeholder when textedBlockCount is 0', async () => {
+		const doc = makeDoc({
+			id: 'doc-1',
+			title: 'Brief ohne Blöcke',
+			annotationCount: 3,
+			textedBlockCount: 0
+		});
+
+		render(TranscriptionColumn, { props: { docs: [doc], weeklyCount: 0 } });
+
+		// The italic em-dash placeholder should render
+		const dashEl = document.querySelector('span.italic');
+		expect(dashEl).not.toBeNull();
+		expect(dashEl?.textContent?.trim()).toBe('—');
+	});
+
+	it('links to /documents/{id}?task=transcribe', async () => {
+		const doc = makeDoc({ id: 'xyz-456', title: 'Transkriptions Dokument' });
+
+		render(TranscriptionColumn, { props: { docs: [doc], weeklyCount: 0 } });
+
+		const link = page.getByRole('link', { name: /Transkriptions Dokument/ });
+		await expect.element(link).toHaveAttribute('href', '/documents/xyz-456?task=transcribe');
+	});
+});