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/routes/documents/[id]/+page.svelte

@@ -1,25 +1,14 @@
 <script lang="ts">
 import { onMount } from 'svelte';
-import { page } from '$app/state';
 import DocumentTopBar from '$lib/components/DocumentTopBar.svelte';
 import DocumentViewer from '$lib/components/DocumentViewer.svelte';
-import AnnotationSidePanel from '$lib/components/AnnotationSidePanel.svelte';
 import TranscriptionEditView from '$lib/components/TranscriptionEditView.svelte';
 import type { TranscriptionBlockData } from '$lib/types';
 
 let { data } = $props();
 
-const targetCommentId = $derived(page.url.searchParams.get('commentId'));
-const targetAnnotationId = $derived(page.url.searchParams.get('annotationId'));
-
 const doc = $derived(data.document);
 const canWrite = $derived(data.canWrite ?? false);
-const canComment = $derived((data.canAnnotate || data.canWrite) ?? false);
-const canAdmin = $derived(
-	(data.user?.groups as Array<{ permissions: string[] }> | undefined)?.some((g) =>
-		g.permissions.includes('ADMIN')
-	) ?? false
-);
 const currentUserId = $derived((data.user?.id as string | undefined) ?? null);
 
 // ── File loading ──────────────────────────────────────────────────────────────
@@ -57,12 +46,10 @@ async function loadFile(id: string) {
 	}
 }
 
-// ── Mode state (mutually exclusive) ──────────────────────────────────────────
+// ── Mode state ───────────────────────────────────────────────────────────────
 
-let annotateMode = $state(false);
 let transcribeMode = $state(false);
 let activeAnnotationId = $state<string | null>(null);
-let activeAnnotationPage = $state<number | null>(null);
 
 // ── Transcription blocks ─────────────────────────────────────────────────────
 
@@ -137,6 +124,18 @@ function handleBlockFocus(blockId: string) {
 	}
 }
 
+function handleAnnotationClick(annotationId: string) {
+	activeAnnotationId = annotationId;
+	// In transcribe mode, focus the block that owns this annotation
+	if (transcribeMode) {
+		const block = transcriptionBlocks.find((b) => b.annotationId === annotationId);
+		if (block) {
+			const el = document.querySelector(`[data-block-id="${block.id}"]`);
+			el?.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
+		}
+	}
+}
+
 // Load blocks when transcribe mode is entered
 $effect(() => {
 	if (transcribeMode) {
@@ -151,10 +150,6 @@ let navHeight = $state(0);
 onMount(() => {
 	navHeight = document.querySelector('header')?.getBoundingClientRect().height ?? 0;
 
-	if (targetAnnotationId) {
-		activeAnnotationId = targetAnnotationId;
-	}
-
 	if (doc?.id) {
 		localStorage.setItem(
 			'familienarchiv.lastVisited',
@@ -163,13 +158,8 @@ onMount(() => {
 	}
 
 	function onKeyDown(e: KeyboardEvent) {
-		if (e.key === 'Escape') {
-			if (transcribeMode) {
-				transcribeMode = false;
-			} else if (activeAnnotationId) {
-				activeAnnotationId = null;
-				activeAnnotationPage = null;
-			}
+		if (e.key === 'Escape' && transcribeMode) {
+			transcribeMode = false;
 		}
 	}
 	document.addEventListener('keydown', onKeyDown);
@@ -189,9 +179,7 @@ onMount(() => {
 	<DocumentTopBar
 		doc={doc}
 		canWrite={canWrite}
-		canAnnotate={data.canAnnotate ?? false}
 		fileUrl={fileUrl}
-		bind:annotateMode={annotateMode}
 		bind:transcribeMode={transcribeMode}
 	/>
 
@@ -202,39 +190,19 @@ onMount(() => {
 				fileUrl={fileUrl}
 				isLoading={isLoading}
 				error={fileError}
-				bind:annotateMode={annotateMode}
 				transcribeMode={transcribeMode}
 				bind:activeAnnotationId={activeAnnotationId}
-				bind:activeAnnotationPage={activeAnnotationPage}
-				onAnnotationClick={(id) => {
-					activeAnnotationId = id;
-				}}
+				onAnnotationClick={handleAnnotationClick}
 				onTranscriptionDraw={createBlockFromDraw}
 			/>
 		</div>
 
-		{#if !transcribeMode}
-			<AnnotationSidePanel
-				documentId={doc.id}
-				activeAnnotationId={activeAnnotationId}
-				activeAnnotationPage={activeAnnotationPage}
-				canComment={canComment}
-				currentUserId={currentUserId}
-				canAdmin={canAdmin}
-				targetCommentId={targetAnnotationId ? targetCommentId : null}
-				onClose={() => {
-					activeAnnotationId = null;
-					activeAnnotationPage = null;
-				}}
-			/>
-		{/if}
-
 		{#if transcribeMode}
 			<div class="w-[400px] shrink-0 border-l border-line lg:w-[480px]">
 				<TranscriptionEditView
 					documentId={doc.id}
 					blocks={transcriptionBlocks}
-					canComment={canComment}
+					canComment={canWrite}
 					currentUserId={currentUserId}
 					onBlockFocus={handleBlockFocus}
 					onSaveBlock={saveBlock}