feat(frontend): hide outdated annotations when file version changes

- Regenerate API types with fileHash on Document and DocumentAnnotation
- PdfViewer accepts documentFileHash prop; filters visibleAnnotations to
  those whose hash matches (or is null) and shows an amber notice banner
  when any annotations are hidden due to a hash mismatch
- Document detail page passes doc.fileHash to PdfViewer
- Add i18n key annotation_outdated_notice in de/en/es
- E2E: two new tests covering hide-on-reupload and restore-on-original-reupload
  scenarios; add minimal2.pdf fixture for a different-hash upload

Closes #55

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

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

@@ -908,6 +908,7 @@ function versionLabel(v: VersionSummary, index: number): string {
 					canComment={canComment}
 					currentUserId={currentUserId}
 					canAdmin={canAdmin}
+					documentFileHash={doc.fileHash ?? null}
 				/>
 			{:else if fileUrl}
 				<div class="flex h-full w-full items-center justify-center overflow-auto p-8">