feat(transcription): add "Alle als fertig markieren" bulk action (#345) (#352)

## Summary

Implements the bulk "Alle als fertig markieren" action for the transcription panel requested in #345.

### Backend

- Added `PUT /api/documents/{documentId}/transcription-blocks/review-all` endpoint to `TranscriptionBlockController`, guarded with `@RequirePermission(Permission.WRITE_ALL)`
- Added `markAllBlocksReviewed(UUID documentId, UUID userId)` to `TranscriptionService` — `@Transactional`, single DB round-trip via `blockRepository.saveAll()`, emits one `BLOCK_REVIEWED` audit event per previously-unreviewed block
- Returns full updated block list (same shape as `listBlocks`) for a clean frontend update pass
- 5 new `TranscriptionServiceTest` unit tests (idempotency, audit events, empty document)
- 5 new `TranscriptionBlockControllerTest` `@WebMvcTest` tests (401, 403, 200 happy path, 200 empty, 401 user not found)
- All 68 backend tests pass

### Frontend

- Added `onMarkAllReviewed?: () => Promise<void>` prop to `TranscriptionEditView` (optional, consistent with `onTriggerOcr` pattern)
- Button placed in sticky progress header, right-aligned next to `reviewedCount / totalCount geprüft`
- Button is **disabled** (not hidden) when all blocks are already reviewed — `title="Alle Blöcke sind bereits als fertig markiert"` (Decision 1)
- Loading spinner replaces checkmark icon during operation — always shown (Decision 4, no threshold)
- Handler `markAllReviewed()` added to `documents/[id]/+page.svelte`, wired as `onMarkAllReviewed`
- 5 new `TranscriptionEditView.svelte.spec.ts` Vitest Browser component tests; all 25 tests pass

### Decisions applied

| # | Question | Choice |
|---|---|---|
| 1 | Button when all reviewed | **Disabled** with `title` tooltip |
| 2 | Audit log | **N individual BLOCK_REVIEWED events** (one per unreviewed block) |
| 3 | Atomicity | **All-or-nothing** via `@Transactional` |
| 4 | Loading indicator | **Always show** during operation |

Closes #345

Co-authored-by: Marcel <marcel@familienarchiv>
Reviewed-on: http://heim-nas:3005/marcel/familienarchiv/pulls/352

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

@@ -137,6 +137,18 @@ async function reviewToggle(blockId: string) {
 	transcriptionBlocks = transcriptionBlocks.map((b) => (b.id === blockId ? updated : b));
 }
 
+async function markAllReviewed() {
+	const res = await fetch(`/api/documents/${doc.id}/transcription-blocks/review-all`, {
+		method: 'PUT'
+	});
+	if (!res.ok) return;
+	const updated = await res.json();
+	for (const b of updated) {
+		const existing = transcriptionBlocks.find((x) => x.id === b.id);
+		if (existing) existing.reviewed = b.reviewed;
+	}
+}
+
 async function toggleTrainingLabel(label: string, enrolled: boolean) {
 	const res = await fetch(`/api/documents/${doc.id}/training-labels`, {
 		method: 'PATCH',
@@ -501,6 +513,7 @@ onMount(() => {
 							onSaveBlock={saveBlock}
 							onDeleteBlock={deleteBlock}
 							onReviewToggle={reviewToggle}
+							onMarkAllReviewed={markAllReviewed}
 							onTriggerOcr={triggerOcr}
 							onToggleTrainingLabel={toggleTrainingLabel}
 						/>