feat(frontend): hide outdated annotations when file version changes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/e2e/fixtures/minimal2.pdf

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