feat(comments): add CommentThread, annotation panel, Diskussion section, and i18n keys

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

frontend/src/routes/documents/[id]/+page.server.ts

@@ -1,19 +1,26 @@
 import { error, redirect } from '@sveltejs/kit';
+import { env } from '$env/dynamic/private';
 import { createApiClient } from '$lib/api.server';
 import { getErrorMessage } from '$lib/errors';
 
 export async function load({ params, fetch }) {
 	const { id } = params;
 	const api = createApiClient(fetch);
+	const base = env.API_INTERNAL_URL || 'http://localhost:8080';
 
-	const result = await api.GET('/api/documents/{id}', { params: { path: { id } } });
+	const [docResult, commentsRes] = await Promise.all([
+		api.GET('/api/documents/{id}', { params: { path: { id } } }),
+		fetch(`${base}/api/documents/${id}/comments`)
+	]);
 
-	if (result.response.status === 401) throw redirect(302, '/login');
+	if (docResult.response.status === 401) throw redirect(302, '/login');
 
-	if (!result.response.ok) {
-		const code = (result.error as unknown as { code?: string })?.code;
-		throw error(result.response.status, getErrorMessage(code));
+	if (!docResult.response.ok) {
+		const code = (docResult.error as unknown as { code?: string })?.code;
+		throw error(docResult.response.status, getErrorMessage(code));
 	}
 
-	return { document: result.data! };
+	const comments = commentsRes.ok ? await commentsRes.json() : [];
+
+	return { document: docResult.data!, comments };
 }

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

@@ -4,10 +4,18 @@ import { formatDate } from '$lib/utils/date';
 import { diffWords } from 'diff';
 import ExpandableText from '$lib/components/ExpandableText.svelte';
 import PdfViewer from '$lib/components/PdfViewer.svelte';
+import CommentThread from '$lib/components/CommentThread.svelte';
 
 let { data } = $props();
 
 const doc = $derived(data.document);
+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);
 
 let fileUrl = $state('');
 let isLoading = $state(false);
@@ -821,6 +829,24 @@ function versionLabel(v: VersionSummary, index: number): string {
 					{/if}
 				</div>
 
+				<!-- 5. DISKUSSION -->
+				<div>
+					<div class="border-b border-brand-sand pb-2">
+						<h3 class="font-sans text-xs font-bold tracking-widest text-brand-navy uppercase">
+							{m.comment_section_title()}
+						</h3>
+					</div>
+					<div class="mt-4">
+						<CommentThread
+							documentId={doc.id}
+							initialComments={data.comments ?? []}
+							canComment={canComment}
+							currentUserId={currentUserId}
+							canAdmin={canAdmin}
+						/>
+					</div>
+				</div>
+
 				<!-- Footer -->
 				<div class="border-t border-brand-sand pt-4 font-sans text-[10px] text-gray-400">
 					<p class="truncate">ID: {doc.id}</p>
@@ -875,7 +901,14 @@ function versionLabel(v: VersionSummary, index: number): string {
 					<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} canAnnotate={data.canAnnotate} />
+				<PdfViewer
+					url={fileUrl}
+					documentId={doc.id}
+					canAnnotate={data.canAnnotate}
+					canComment={canComment}
+					currentUserId={currentUserId}
+					canAdmin={canAdmin}
+				/>
 			{:else if fileUrl}
 				<div class="flex h-full w-full items-center justify-center overflow-auto p-8">
 					<img