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/annotation/AnnotationLayer.svelte.spec.ts

@@ -0,0 +1,125 @@
+import { describe, it, expect, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+
+import AnnotationLayer from './AnnotationLayer.svelte';
+
+afterEach(cleanup);
+
+type Annotation = {
+	id: string;
+	documentId: string;
+	pageNumber: number;
+	x: number;
+	y: number;
+	width: number;
+	height: number;
+	color: string;
+	createdAt: string;
+};
+
+function makeAnnotation(id = 'ann-1', color = '#00C7B1'): Annotation {
+	return {
+		id,
+		documentId: 'doc-1',
+		pageNumber: 1,
+		x: 0.1,
+		y: 0.1,
+		width: 0.3,
+		height: 0.2,
+		color,
+		createdAt: new Date().toISOString()
+	};
+}
+
+describe('AnnotationLayer', () => {
+	it('renders a colored element for each annotation', async () => {
+		render(AnnotationLayer, {
+			annotations: [makeAnnotation('ann-1'), makeAnnotation('ann-2')],
+			canDraw: false,
+			color: '#00C7B1',
+			onDraw: () => {}
+		});
+
+		await expect.element(page.getByTestId('annotation-ann-1')).toBeInTheDocument();
+		await expect.element(page.getByTestId('annotation-ann-2')).toBeInTheDocument();
+	});
+
+	it('has crosshair cursor when canDraw is true', async () => {
+		render(AnnotationLayer, {
+			annotations: [],
+			canDraw: true,
+			color: '#00C7B1',
+			onDraw: () => {}
+		});
+
+		const container = document.querySelector('[role="presentation"]')!;
+		expect(container.getAttribute('style')).toContain('cursor: crosshair');
+	});
+
+	it('does not have crosshair cursor when canDraw is false', async () => {
+		render(AnnotationLayer, {
+			annotations: [],
+			canDraw: false,
+			color: '#00C7B1',
+			onDraw: () => {}
+		});
+
+		const container = document.querySelector('[role="presentation"]')!;
+		expect(container.getAttribute('style')).not.toContain('cursor: crosshair');
+	});
+
+	it('dims non-active annotations when activeAnnotationId is set', async () => {
+		render(AnnotationLayer, {
+			annotations: [makeAnnotation('ann-1'), makeAnnotation('ann-2')],
+			canDraw: false,
+			color: '#00C7B1',
+			activeAnnotationId: 'ann-1',
+			onDraw: () => {}
+		});
+
+		const active = page.getByTestId('annotation-ann-1').element();
+		const dimmed = page.getByTestId('annotation-ann-2').element();
+		expect(active.style.opacity).toBe('1');
+		expect(dimmed.style.opacity).toBe('0.3');
+	});
+
+	it('shows all annotations at full opacity when no activeAnnotationId', async () => {
+		render(AnnotationLayer, {
+			annotations: [makeAnnotation('ann-1'), makeAnnotation('ann-2')],
+			canDraw: false,
+			color: '#00C7B1',
+			onDraw: () => {}
+		});
+
+		const el1 = page.getByTestId('annotation-ann-1').element();
+		const el2 = page.getByTestId('annotation-ann-2').element();
+		expect(el1.style.opacity).toBe('1');
+		expect(el2.style.opacity).toBe('1');
+	});
+
+	it('does not show delete button when annotation is not hovered or active', async () => {
+		render(AnnotationLayer, {
+			annotations: [makeAnnotation('ann-1')],
+			canDraw: true,
+			color: '#00C7B1',
+			onDraw: () => {}
+		});
+
+		await expect.element(page.getByTestId('annotation-ann-1')).toBeInTheDocument();
+		expect(page.getByTestId('annotation-delete-ann-1').query()).toBeNull();
+	});
+
+	it('does not show delete button when canDraw is false even if annotation is active', async () => {
+		render(AnnotationLayer, {
+			annotations: [makeAnnotation('ann-1')],
+			canDraw: false,
+			color: '#00C7B1',
+			activeAnnotationId: 'ann-1',
+			onDraw: () => {}
+		});
+
+		await expect.element(page.getByTestId('annotation-ann-1')).toBeInTheDocument();
+		expect(page.getByTestId('annotation-delete-ann-1').query()).toBeNull();
+	});
+});