feat(frontend): wire OCR trigger + review toggle into transcription panel

- OcrTrigger component rendered in the transcription empty state when
  the document has a file and user has write permission
- Review checkmark toggle on each TranscriptionBlock (turquoise when
  reviewed, muted outline when not). Calls PUT .../review to toggle.
- TranscriptionBlockData type: added source + reviewed fields
- +page.svelte: triggerOcr() and reviewToggle() functions wired up
- Paraglide translations (de/en/es) for review toggle + reviewed count

All 687 frontend tests pass.

Refs #226, #230

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

frontend/src/lib/components/TranscriptionEditView.svelte

@@ -2,6 +2,7 @@
 import { m } from '$lib/paraglide/messages.js';
 import { SvelteMap } from 'svelte/reactivity';
 import TranscriptionBlock from './TranscriptionBlock.svelte';
+import OcrTrigger from './OcrTrigger.svelte';
 import type { TranscriptionBlockData } from '$lib/types';
 
 type SaveState = 'idle' | 'saving' | 'saved' | 'fading' | 'error';
@@ -12,9 +13,13 @@ type Props = {
 	canComment: boolean;
 	currentUserId: string | null;
 	activeAnnotationId?: string | null;
+	storedScriptType?: string;
+	canRunOcr?: boolean;
 	onBlockFocus: (blockId: string) => void;
 	onSaveBlock: (blockId: string, text: string) => Promise<void>;
 	onDeleteBlock: (blockId: string) => Promise<void>;
+	onReviewToggle: (blockId: string) => Promise<void>;
+	onTriggerOcr?: (scriptType: string) => void;
 };
 
 let {
@@ -23,9 +28,13 @@ let {
 	canComment,
 	currentUserId,
 	activeAnnotationId = null,
+	storedScriptType = '',
+	canRunOcr = false,
 	onBlockFocus,
 	onSaveBlock,
-	onDeleteBlock
+	onDeleteBlock,
+	onReviewToggle,
+	onTriggerOcr
 }: Props = $props();
 
 let activeBlockId: string | null = $state(null);
@@ -282,6 +291,7 @@ $effect(() => {
 						text={block.text}
 						label={block.label}
 						active={activeBlockId === block.id}
+						reviewed={block.reviewed ?? false}
 						saveState={getSaveState(block.id)}
 						canComment={canComment}
 						currentUserId={currentUserId}
@@ -289,6 +299,7 @@ $effect(() => {
 						onFocus={() => handleFocus(block.id)}
 						onDeleteClick={() => handleDelete(block.id)}
 						onRetry={() => handleRetry(block.id)}
+						onReviewToggle={() => onReviewToggle(block.id)}
 						onMoveUp={() => handleMoveUp(block.id)}
 						onMoveDown={() => handleMoveDown(block.id)}
 						isFirst={i === 0}
@@ -323,9 +334,26 @@ $effect(() => {
 					d="M19.5 14.25v-2.625a3.375 3.375 0 00-3.375-3.375h-1.5A1.125 1.125 0 0113.5 7.125v-1.5a3.375 3.375 0 00-3.375-3.375H8.25m0 12.75h7.5m-7.5 3H12M10.5 2.25H5.625c-.621 0-1.125.504-1.125 1.125v17.25c0 .621.504 1.125 1.125 1.125h12.75c.621 0 1.125-.504 1.125-1.125V11.25a9 9 0 00-9-9z"
 				/>
 			</svg>
-			<p class="max-w-xs text-sm leading-relaxed text-ink-3">
-				{m.transcription_empty_cta()}
-			</p>
+
+			{#if canRunOcr && onTriggerOcr}
+				<p class="mb-6 max-w-xs text-sm leading-relaxed text-ink-3">
+					{m.transcription_empty_title()}
+				</p>
+				<div class="w-full max-w-xs">
+					<OcrTrigger
+						existingBlockCount={0}
+						storedScriptType={storedScriptType}
+						onTrigger={onTriggerOcr}
+					/>
+				</div>
+				<p class="mt-4 text-xs text-ink-3">
+					{m.transcription_empty_desc()}
+				</p>
+			{:else}
+				<p class="max-w-xs text-sm leading-relaxed text-ink-3">
+					{m.transcription_empty_cta()}
+				</p>
+			{/if}
 		</div>
 	{/if}
 </div>