feat(admin): add READ_ALL and ANNOTATE_ALL to groups permission matrix

Adds 'Nur lesen' (READ_ALL) and 'Lesen & Annotieren' (ANNOTATE_ALL)
as standard permission options alongside the existing 'Lesen & Schreiben'
(WRITE_ALL), ordered from least to most access.

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

frontend/src/routes/admin/groups/[id]/+page.svelte

@@ -25,6 +25,8 @@ $effect(() => {
 });
 
 const STANDARD_PERMISSIONS: { value: string; label: string }[] = [
+	{ value: 'READ_ALL', label: 'Nur lesen' },
+	{ value: 'ANNOTATE_ALL', label: 'Lesen & Annotieren' },
 	{ value: 'WRITE_ALL', label: 'Lesen & Schreiben' }
 ];