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/TranscriptionBlock.svelte

@@ -14,6 +14,7 @@ type Props = {
 	text: string;
 	label: string | null;
 	active: boolean;
+	reviewed: boolean;
 	saveState: SaveState;
 	canComment: boolean;
 	currentUserId: string | null;
@@ -21,6 +22,7 @@ type Props = {
 	onFocus: () => void;
 	onDeleteClick: () => void;
 	onRetry: () => void;
+	onReviewToggle: () => void;
 	onMoveUp?: () => void;
 	onMoveDown?: () => void;
 	isFirst?: boolean;
@@ -34,6 +36,7 @@ let {
 	text,
 	label = null,
 	active,
+	reviewed,
 	saveState,
 	canComment,
 	currentUserId,
@@ -41,6 +44,7 @@ let {
 	onFocus,
 	onDeleteClick,
 	onRetry,
+	onReviewToggle,
 	onMoveUp,
 	onMoveDown,
 	isFirst = false,
@@ -239,6 +243,29 @@ function handleTextareaMouseUp() {
 					</span>
 				{/if}
 
+				<!-- Review toggle -->
+				<button
+					type="button"
+					class="cursor-pointer transition-colors {reviewed ? 'text-turquoise hover:text-turquoise/70' : 'text-ink-3 hover:text-turquoise'}"
+					aria-label={reviewed ? m.transcription_block_unreview() : m.transcription_block_review()}
+					title={reviewed ? m.transcription_block_unreview() : m.transcription_block_review()}
+					onclick={onReviewToggle}
+				>
+					<svg
+						class="h-4 w-4"
+						fill={reviewed ? 'currentColor' : 'none'}
+						viewBox="0 0 24 24"
+						stroke="currentColor"
+						stroke-width="1.5"
+					>
+						<path
+							stroke-linecap="round"
+							stroke-linejoin="round"
+							d="M9 12.75L11.25 15 15 9.75M21 12a9 9 0 11-18 0 9 9 0 0118 0z"
+						/>
+					</svg>
+				</button>
+
 				<!-- Delete button -->
 				<button
 					type="button"