refactor: remove legacy annotate mode — transcription replaces it

The yellow annotation+comment system is now redundant. Transcription
blocks handle the same use case (mark region → discuss) but better,
because they also produce a transcription.

Removed:
- annotateMode state and all wiring through page/topbar/viewer/pdfviewer
- Annotate/Stop annotate buttons from DocumentTopBar
- AnnotateHintStrip import and rendering
- AnnotationSidePanel from document detail page
- canAnnotate prop from DocumentTopBar
- Color picker from PdfViewer
- Comment count badges and loadCommentCounts from PdfViewer
- Delete button from AnnotationLayer (blocks own annotation lifecycle)
- dimColor prop from AnnotationLayer

Simplified:
- AnnotationLayer: only canDraw + color + onDraw + onAnnotationClick
- PdfViewer: only draws in transcribeMode with turquoise
- Clicking annotation in transcribe mode scrolls to corresponding block
- canComment derived from canWrite (no longer needs canAnnotate)

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

frontend/src/lib/components/PdfViewer.svelte

@@ -1,6 +1,5 @@
 <script lang="ts">
 import { onMount } from 'svelte';
-import { SvelteMap } from 'svelte/reactivity';
 import type { PDFDocumentProxy, PDFPageProxy, RenderTask } from 'pdfjs-dist';
 import AnnotationLayer from './AnnotationLayer.svelte';
 import type { Annotation } from '$lib/types';
@@ -11,20 +10,16 @@ type DrawRect = { x: number; y: number; width: number; height: number; pageNumbe
 let {
 	url,
 	documentId = '',
-	annotateMode = $bindable(false),
 	transcribeMode = false,
 	activeAnnotationId = $bindable<string | null>(null),
-	activeAnnotationPage = $bindable<number | null>(null),
 	onAnnotationClick,
 	onTranscriptionDraw,
 	documentFileHash
 }: {
 	url: string;
 	documentId?: string;
-	annotateMode?: boolean;
 	transcribeMode?: boolean;
 	activeAnnotationId?: string | null;
-	activeAnnotationPage?: number | null;
 	onAnnotationClick?: (id: string) => void;
 	onTranscriptionDraw?: (rect: DrawRect) => void;
 	documentFileHash?: string | null;
@@ -51,13 +46,9 @@ let pdfjsLib: typeof import('pdfjs-dist') | null = null;
 let pdfjsReady = $state(false);
 
 let annotations = $state<Annotation[]>([]);
-let annotateColor = $state('#ffff00');
-let commentCounts = new SvelteMap<string, number>();
 let showAnnotations = $state(true);
 
 const TRANSCRIPTION_COLOR = '#00C7B1';
-const drawingEnabled = $derived(annotateMode || transcribeMode);
-const drawColor = $derived(transcribeMode ? TRANSCRIPTION_COLOR : annotateColor);
 
 const visibleAnnotations = $derived(
 	annotations.filter((a) => !a.fileHash || !documentFileHash || a.fileHash === documentFileHash)
@@ -174,30 +165,12 @@ async function prerender(doc: PDFDocumentProxy, pageNum: number) {
 	}
 }
 
-async function loadCommentCounts(docId: string, anns: Annotation[]) {
-	await Promise.all(
-		anns.map(async (a) => {
-			try {
-				const res = await fetch(`/api/documents/${docId}/annotations/${a.id}/comments`);
-				if (res.ok) {
-					const threads = (await res.json()) as Array<{ replies: unknown[] }>;
-					const total = threads.reduce((sum, t) => sum + 1 + t.replies.length, 0);
-					commentCounts.set(a.id, total);
-				}
-			} catch {
-				// ignore
-			}
-		})
-	);
-}
-
 async function loadAnnotations(docId: string) {
 	if (!docId) return;
 	try {
 		const res = await fetch(`/api/documents/${docId}/annotations`);
 		if (res.ok) {
 			annotations = await res.json();
-			await loadCommentCounts(docId, annotations);
 		}
 	} catch {
 		// ignore
@@ -205,57 +178,13 @@ async function loadAnnotations(docId: string) {
 }
 
 async function handleDraw(rect: { x: number; y: number; width: number; height: number }) {
-	if (!documentId) return;
-
-	if (transcribeMode) {
-		await onTranscriptionDraw?.({ ...rect, pageNumber: currentPage });
-		await loadAnnotations(documentId);
-		return;
-	}
-
-	try {
-		const res = await fetch(`/api/documents/${documentId}/annotations`, {
-			method: 'POST',
-			headers: { 'Content-Type': 'application/json' },
-			body: JSON.stringify({
-				pageNumber: currentPage,
-				x: rect.x,
-				y: rect.y,
-				width: rect.width,
-				height: rect.height,
-				color: annotateColor
-			})
-		});
-		if (res.ok) {
-			const created: Annotation = await res.json();
-			annotations = [...annotations, created];
-			activeAnnotationId = created.id;
-			activeAnnotationPage = created.pageNumber;
-			onAnnotationClick?.(created.id);
-		}
-	} catch {
-		// ignore
-	}
-}
-
-async function handleAnnotationDelete(annotationId: string) {
-	if (!documentId) return;
-	try {
-		const res = await fetch(`/api/documents/${documentId}/annotations/${annotationId}`, {
-			method: 'DELETE'
-		});
-		if (res.ok) {
-			annotations = annotations.filter((a) => a.id !== annotationId);
-		}
-	} catch {
-		// ignore
-	}
+	if (!documentId || !transcribeMode) return;
+	await onTranscriptionDraw?.({ ...rect, pageNumber: currentPage });
+	await loadAnnotations(documentId);
 }
 
 function handleAnnotationClick(id: string) {
 	activeAnnotationId = id;
-	const ann = annotations.find((a) => a.id === id);
-	activeAnnotationPage = ann?.pageNumber ?? null;
 	onAnnotationClick?.(id);
 }
 
@@ -283,7 +212,7 @@ $effect(() => {
 });
 
 $effect(() => {
-	if (annotateMode) showAnnotations = true;
+	if (transcribeMode) showAnnotations = true;
 });
 
 function prevPage() {
@@ -429,16 +358,6 @@ function zoomOut() {
 				</button>
 			</div>
 
-			<!-- Color picker (shown in annotate mode) -->
-			{#if annotateMode}
-				<input
-					type="color"
-					bind:value={annotateColor}
-					aria-label="Farbe wählen"
-					class="h-6 w-6 cursor-pointer rounded border-0 bg-transparent p-0"
-					title="Farbe wählen"
-				/>
-			{/if}
 			<!-- Annotation visibility toggle (shown when annotations exist) -->
 			{#if annotations.length > 0}
 				<button
@@ -503,12 +422,9 @@ function zoomOut() {
 						{#if showAnnotations}
 							<AnnotationLayer
 								annotations={visibleAnnotations.filter((a) => a.pageNumber === currentPage)}
-								canAnnotate={drawingEnabled}
-								color={drawColor}
-								dimColor={transcribeMode ? '#ffff00' : annotateMode ? TRANSCRIPTION_COLOR : undefined}
+								canDraw={transcribeMode}
+								color={TRANSCRIPTION_COLOR}
 								onDraw={handleDraw}
-								onDelete={handleAnnotationDelete}
-								commentCounts={Object.fromEntries(commentCounts)}
 								onAnnotationClick={handleAnnotationClick}
 							/>
 						{/if}